diff --git a/README.md b/README.md
index 7707d966..5f2e4d26 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,7 @@ opinions. Please communicate with us on [Slack](https://t.mp/slack) in the `#rub
     - [Cloud Client Using API Key](#cloud-client-using-api-key)
     - [Data Conversion](#data-conversion)
       - [ActiveModel](#activemodel)
+      - [Converter Hints](#converter-hints)
   - [Workers](#workers)
   - [Workflows](#workflows)
     - [Workflow Definition](#workflow-definition)
@@ -336,6 +337,25 @@ Now if `include ActiveModelJSONSupport` is present on any ActiveModel class, on
 which will use `as_json` which calls the super `as_json` but also includes the fully qualified class name as the JSON
 `create_id` key. On deserialization, Ruby JSON then uses this key to know what class to call `json_create` on.
 
+##### Converter Hints
+
+In most places where objects are converted to payloads or vice versa, a "hint" can be provided to tell the converter
+something else about the object/payload to assist conversion. The default converters ignore these hints, but custom
+converters can be written to take advantage of them. For example, hints may be used to provide a custom converter the
+Ruby type to deserialize a payload into.
+
+These hints manifest themselves various ways throughout the API. The most obvious way is when making definitions. An
+activity can define `activity_arg_hint` (which accepts multiple) and/or `activity_result_hint` for activity-level hints.
+Similarly, a workflow can define `workflow_arg_hint` and/or `workflow_result_hint` for workflow-level hints.
+`workflow_signal`, `workflow_query`, and `workflow_update` all similarly accept `arg_hints` and `result_hint` (except
+signal of course). These definition-level hints are passed to converters both from the caller side and the
+implementation side.
+
+There are some advanced payload uses in the SDK that do not currently have a way to set hints. These include
+workflow/schedule memo, workflow get/upsert memo, activity last heartbeat details, and application error details. In
+some cases, users can use `Temporalio::Converters::RawValue` and then manually convert with hints. For others, hints can
+be added as needed, please open an issue or otherwise contact Temporal.
+
 ### Workers
 
 Workers host workflows and/or activities. Here's how to run a worker:
diff --git a/temporalio/lib/temporalio/activity/context.rb b/temporalio/lib/temporalio/activity/context.rb
index 64bdfb17..4e8ee734 100644
--- a/temporalio/lib/temporalio/activity/context.rb
+++ b/temporalio/lib/temporalio/activity/context.rb
@@ -61,7 +61,8 @@ def instance
       # Users do not have to be concerned with burdening the server by calling this too frequently.
       #
       # @param details [Array<Object>] Details to record with the heartbeat.
-      def heartbeat(*details)
+      # @param detail_hints [Array<Object>, nil] Hints to pass to converter.
+      def heartbeat(*details, detail_hints: nil)
         raise NotImplementedError
       end
 
diff --git a/temporalio/lib/temporalio/activity/definition.rb b/temporalio/lib/temporalio/activity/definition.rb
index 4941c4c9..10637a81 100644
--- a/temporalio/lib/temporalio/activity/definition.rb
+++ b/temporalio/lib/temporalio/activity/definition.rb
@@ -78,6 +78,21 @@ def activity_raw_args(value = true) # rubocop:disable Style/OptionalBooleanParam
 
           @activity_raw_args = value
         end
+
+        # Add activity hints to be passed to converter for activity args.
+        #
+        # @param hints [Array<Object>] Hints to add.
+        def activity_arg_hint(*hints)
+          @activity_arg_hints ||= []
+          @activity_arg_hints.concat(hints)
+        end
+
+        # Set activity result hint to be passed to converter for activity result.
+        #
+        # @param hint [Object] Hint to set.
+        def activity_result_hint(hint)
+          @activity_result_hint = hint
+        end
       end
 
       # @!visibility private
@@ -96,7 +111,9 @@ def self._activity_definition_details
           activity_name:,
           activity_executor: @activity_executor || :default,
           activity_cancel_raise: @activity_cancel_raise.nil? || @activity_cancel_raise,
-          activity_raw_args: @activity_raw_args.nil? ? false : @activity_raw_args
+          activity_raw_args: @activity_raw_args.nil? ? false : @activity_raw_args,
+          activity_arg_hints: @activity_arg_hints,
+          activity_result_hint: @activity_result_hint
         }
       end
 
@@ -127,6 +144,12 @@ class Info
         # @return [Boolean] Whether to use {Converters::RawValue}s as arguments.
         attr_reader :raw_args
 
+        # @return [Array<Object>, nil] Argument hints.
+        attr_reader :arg_hints
+
+        # @return [Object, nil] Result hint
+        attr_reader :result_hint
+
         # Obtain definition info representing the given activity, which can be a class, instance, or definition info.
         #
         # @param activity [Definition, Class<Definition>, Info] Activity to get info for.
@@ -147,7 +170,9 @@ def self.from_activity(activity)
               instance: proc { activity.new },
               executor: details[:activity_executor],
               cancel_raise: details[:activity_cancel_raise],
-              raw_args: details[:activity_raw_args]
+              raw_args: details[:activity_raw_args],
+              arg_hints: details[:activity_arg_hints],
+              result_hint: details[:activity_result_hint]
             ) { |*args| Context.current.instance&.execute(*args) }
           when Definition
             details = activity.class._activity_definition_details
@@ -156,7 +181,9 @@ def self.from_activity(activity)
               instance: activity,
               executor: details[:activity_executor],
               cancel_raise: details[:activity_cancel_raise],
-              raw_args: details[:activity_raw_args]
+              raw_args: details[:activity_raw_args],
+              arg_hints: details[:activity_arg_hints],
+              result_hint: details[:activity_result_hint]
             ) { |*args| Context.current.instance&.execute(*args) }
           when Info
             activity
@@ -172,6 +199,8 @@ def self.from_activity(activity)
         # @param executor [Symbol] Name of the executor.
         # @param cancel_raise [Boolean] Whether to raise in thread/fiber on cancellation.
         # @param raw_args [Boolean] Whether to use {Converters::RawValue}s as arguments.
+        # @param arg_hints [Array<Object>, nil] Argument hints.
+        # @param result_hint [Object, nil] Result hint.
         # @yield Use this block as the activity.
         def initialize(
           name:,
@@ -179,6 +208,8 @@ def initialize(
           executor: :default,
           cancel_raise: true,
           raw_args: false,
+          arg_hints: nil,
+          result_hint: nil,
           &block
         )
           @name = name
@@ -189,6 +220,8 @@ def initialize(
           @executor = executor
           @cancel_raise = cancel_raise
           @raw_args = raw_args
+          @arg_hints = arg_hints
+          @result_hint = result_hint
           Internal::ProtoUtils.assert_non_reserved_name(name)
         end
       end
diff --git a/temporalio/lib/temporalio/client.rb b/temporalio/lib/temporalio/client.rb
index b18a6bfd..b60f3c6e 100644
--- a/temporalio/lib/temporalio/client.rb
+++ b/temporalio/lib/temporalio/client.rb
@@ -231,6 +231,10 @@ def operator_service
     # @param versioning_override [VersioningOverride, nil] Override the version of the workflow.
     #   This is currently experimental.
     # @param priority [Priority] Priority of the workflow. This is currently experimental.
+    # @param arg_hints [Array<Object>, nil] Overrides converter hints for arguments if any. If unset/nil and the
+    #   workflow definition has arg hints, those are used by default.
+    # @param result_hint [Object, nil] Overrides converter hint for result if any. If unset/nil and the workflow
+    #   definition has result hint, it is used by default.
     # @param rpc_options [RPCOptions, nil] Advanced RPC options.
     #
     # @return [WorkflowHandle] A workflow handle to the started workflow.
@@ -256,10 +260,15 @@ def start_workflow(
       request_eager_start: false,
       versioning_override: nil,
       priority: Priority.default,
+      arg_hints: nil,
+      result_hint: nil,
       rpc_options: nil
     )
+      # Take hints from definition if there is a definition
+      workflow, defn_arg_hints, defn_result_hint =
+        Workflow::Definition._workflow_type_and_hints_from_workflow_parameter(workflow)
       @impl.start_workflow(Interceptor::StartWorkflowInput.new(
-                             workflow: Workflow::Definition._workflow_type_from_workflow_parameter(workflow),
+                             workflow:,
                              args:,
                              workflow_id: id,
                              task_queue:,
@@ -279,6 +288,8 @@ def start_workflow(
                              headers: {},
                              versioning_override:,
                              priority:,
+                             arg_hints: arg_hints || defn_arg_hints,
+                             result_hint: result_hint || defn_result_hint,
                              rpc_options:
                            ))
     end
@@ -314,6 +325,10 @@ def start_workflow(
     # @param versioning_override [VersioningOverride, nil] Override the version of the workflow.
     #   This is currently experimental.
     # @param priority [Priority] Priority for the workflow. This is currently experimental.
+    # @param arg_hints [Array<Object>, nil] Overrides converter hints for arguments if any. If unset/nil and the
+    #   workflow definition has arg hints, those are used by default.
+    # @param result_hint [Object, nil] Overrides converter hint for result if any. If unset/nil and the workflow
+    #   definition has result hint, it is used by default.
     # @param rpc_options [RPCOptions, nil] Advanced RPC options.
     #
     # @return [Object] Successful result of the workflow.
@@ -340,10 +355,11 @@ def execute_workflow(
       request_eager_start: false,
       versioning_override: nil,
       priority: Priority.default,
-      follow_runs: true,
+      arg_hints: nil,
+      result_hint: nil,
       rpc_options: nil
     )
-      handle = start_workflow(
+      start_workflow(
         workflow,
         *args,
         id:,
@@ -363,9 +379,10 @@ def execute_workflow(
         request_eager_start:,
         versioning_override:,
         priority:,
+        arg_hints:,
+        result_hint:,
         rpc_options:
-      )
-      follow_runs ? handle.result : handle
+      ).result
     end
 
     # Get a workflow handle to an existing workflow by its ID.
@@ -375,14 +392,18 @@ def execute_workflow(
     #   interactions occur on the latest of the workflow ID.
     # @param first_execution_run_id [String, nil] First execution run ID used for some calls like cancellation and
     #   termination to ensure the affected workflow is only within the same chain as this given run ID.
+    # @param result_hint [Object, nil] Converter hint for the workflow's result.
     #
     # @return [WorkflowHandle] The workflow handle.
     def workflow_handle(
       workflow_id,
       run_id: nil,
-      first_execution_run_id: nil
+      first_execution_run_id: nil,
+      result_hint: nil
     )
-      WorkflowHandle.new(client: self, id: workflow_id, run_id:, result_run_id: run_id, first_execution_run_id:)
+      WorkflowHandle.new(
+        client: self, id: workflow_id, run_id:, result_run_id: run_id, first_execution_run_id:, result_hint:
+      )
     end
 
     # Start an update, possibly starting the workflow at the same time if it doesn't exist (depending upon ID conflict
@@ -396,6 +417,10 @@ def workflow_handle(
     # @param wait_for_stage [WorkflowUpdateWaitStage] Required stage to wait until returning. ADMITTED is not
     #   currently supported. See https://docs.temporal.io/workflows#update for more details.
     # @param id [String] ID of the update.
+    # @param arg_hints [Array<Object>, nil] Overrides converter hints for update arguments if any. If unset/nil and the
+    #   update definition has arg hints, those are used by default.
+    # @param result_hint [Object, nil] Overrides converter hint for update result if any. If unset/nil and the update
+    #   definition has result hint, it is used by default.
     # @param rpc_options [RPCOptions, nil] Advanced RPC options.
     #
     # @return [WorkflowUpdateHandle] The update handle.
@@ -409,15 +434,20 @@ def start_update_with_start_workflow(
       start_workflow_operation:,
       wait_for_stage:,
       id: SecureRandom.uuid,
+      arg_hints: nil,
+      result_hint: nil,
       rpc_options: nil
     )
+      update, defn_arg_hints, defn_result_hint = Workflow::Definition::Update._name_and_hints_from_parameter(update)
       @impl.start_update_with_start_workflow(
         Interceptor::StartUpdateWithStartWorkflowInput.new(
           update_id: id,
-          update: Workflow::Definition::Update._name_from_parameter(update),
+          update:,
           args:,
           wait_for_stage:,
           start_workflow_operation:,
+          arg_hints: arg_hints || defn_arg_hints,
+          result_hint: result_hint || defn_result_hint,
           headers: {},
           rpc_options:
         )
@@ -433,6 +463,10 @@ def start_update_with_start_workflow(
     # @param start_workflow_operation [WithStartWorkflowOperation] Required with-start workflow operation. This must
     #   have an `id_conflict_policy` set.
     # @param id [String] ID of the update.
+    # @param arg_hints [Array<Object>, nil] Overrides converter hints for update arguments if any. If unset/nil and the
+    #   update definition has arg hints, those are used by default.
+    # @param result_hint [Object, nil] Overrides converter hint for update result if any. If unset/nil and the update
+    #   definition has result hint, it is used by default.
     # @param rpc_options [RPCOptions, nil] Advanced RPC options.
     #
     # @return [Object] Successful update result.
@@ -446,6 +480,8 @@ def execute_update_with_start_workflow(
       *args,
       start_workflow_operation:,
       id: SecureRandom.uuid,
+      arg_hints: nil,
+      result_hint: nil,
       rpc_options: nil
     )
       start_update_with_start_workflow(
@@ -454,6 +490,8 @@ def execute_update_with_start_workflow(
         start_workflow_operation:,
         wait_for_stage: WorkflowUpdateWaitStage::COMPLETED,
         id:,
+        arg_hints:,
+        result_hint:,
         rpc_options:
       ).result
     end
@@ -464,6 +502,8 @@ def execute_update_with_start_workflow(
     # @param args [Array<Object>] Signal arguments.
     # @param start_workflow_operation [WithStartWorkflowOperation] Required with-start workflow operation. This may not
     #   support all `id_conflict_policy` options.
+    # @param arg_hints [Array<Object>, nil] Overrides converter hints for signal arguments if any. If unset/nil and the
+    #   signal definition has arg hints, those are used by default.
     # @param rpc_options [RPCOptions, nil] Advanced RPC options.
     #
     # @return [WorkflowHandle] A workflow handle to the workflow.
@@ -473,13 +513,16 @@ def signal_with_start_workflow(
       signal,
       *args,
       start_workflow_operation:,
+      arg_hints: nil,
       rpc_options: nil
     )
+      signal, defn_arg_hints = Workflow::Definition::Signal._name_and_hints_from_parameter(signal)
       @impl.signal_with_start_workflow(
         Interceptor::SignalWithStartWorkflowInput.new(
-          signal: Workflow::Definition::Signal._name_from_parameter(signal),
+          signal:,
           args:,
           start_workflow_operation:,
+          arg_hints: arg_hints || defn_arg_hints,
           rpc_options:
         )
       )
diff --git a/temporalio/lib/temporalio/client/async_activity_handle.rb b/temporalio/lib/temporalio/client/async_activity_handle.rb
index 4a94467d..2010a6c3 100644
--- a/temporalio/lib/temporalio/client/async_activity_handle.rb
+++ b/temporalio/lib/temporalio/client/async_activity_handle.rb
@@ -27,11 +27,13 @@ def initialize(client:, task_token:, id_reference:)
       # Record a heartbeat for the activity.
       #
       # @param details [Array<Object>] Details of the heartbeat.
+      # @param detail_hints [Array<Object>, nil] Converter hints for the details.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
-      def heartbeat(*details, rpc_options: nil)
+      def heartbeat(*details, detail_hints: nil, rpc_options: nil)
         @client._impl.heartbeat_async_activity(Interceptor::HeartbeatAsyncActivityInput.new(
                                                  task_token_or_id_reference:,
                                                  details:,
+                                                 detail_hints:,
                                                  rpc_options:
                                                ))
       end
@@ -39,11 +41,13 @@ def heartbeat(*details, rpc_options: nil)
       # Complete the activity.
       #
       # @param result [Object, nil] Result of the activity.
+      # @param result_hint [Object, nil] Converter hint for the result.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
-      def complete(result = nil, rpc_options: nil)
+      def complete(result = nil, result_hint: nil, rpc_options: nil)
         @client._impl.complete_async_activity(Interceptor::CompleteAsyncActivityInput.new(
                                                 task_token_or_id_reference:,
                                                 result:,
+                                                result_hint:,
                                                 rpc_options:
                                               ))
       end
@@ -52,12 +56,14 @@ def complete(result = nil, rpc_options: nil)
       #
       # @param error [Exception] Error for the activity.
       # @param last_heartbeat_details [Array<Object>] Last heartbeat details for the activity.
+      # @param last_heartbeat_detail_hints [Array<Object>, nil] Converter hints for the last heartbeat details.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
-      def fail(error, last_heartbeat_details: [], rpc_options: nil)
+      def fail(error, last_heartbeat_details: [], last_heartbeat_detail_hints: nil, rpc_options: nil)
         @client._impl.fail_async_activity(Interceptor::FailAsyncActivityInput.new(
                                             task_token_or_id_reference:,
                                             error:,
                                             last_heartbeat_details:,
+                                            last_heartbeat_detail_hints:,
                                             rpc_options:
                                           ))
       end
@@ -65,12 +71,14 @@ def fail(error, last_heartbeat_details: [], rpc_options: nil)
       # Report the activity as canceled.
       #
       # @param details [Array<Object>] Cancellation details.
+      # @param detail_hints [Array<Object>, nil] Converter hints for the details.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
       # @raise [AsyncActivityCanceledError] If the activity has been canceled.
-      def report_cancellation(*details, rpc_options: nil)
+      def report_cancellation(*details, detail_hints: nil, rpc_options: nil)
         @client._impl.report_cancellation_async_activity(Interceptor::ReportCancellationAsyncActivityInput.new(
                                                            task_token_or_id_reference:,
                                                            details:,
+                                                           detail_hints:,
                                                            rpc_options:
                                                          ))
       end
diff --git a/temporalio/lib/temporalio/client/interceptor.rb b/temporalio/lib/temporalio/client/interceptor.rb
index f039dfab..361acd1c 100644
--- a/temporalio/lib/temporalio/client/interceptor.rb
+++ b/temporalio/lib/temporalio/client/interceptor.rb
@@ -36,9 +36,11 @@ def intercept_client(next_interceptor)
         :search_attributes,
         :start_delay,
         :request_eager_start,
-        :headers,
         :versioning_override,
         :priority,
+        :arg_hints,
+        :result_hint,
+        :headers,
         :rpc_options
       )
 
@@ -49,6 +51,8 @@ def intercept_client(next_interceptor)
         :args,
         :wait_for_stage,
         :start_workflow_operation,
+        :arg_hints,
+        :result_hint,
         :headers,
         :rpc_options
       )
@@ -58,6 +62,7 @@ def intercept_client(next_interceptor)
         :signal,
         :args,
         :start_workflow_operation,
+        :arg_hints,
         # Headers intentionally not defined here, because they are not separate from start_workflow_operation
         :rpc_options
       )
@@ -99,6 +104,7 @@ def intercept_client(next_interceptor)
         :run_id,
         :signal,
         :args,
+        :arg_hints,
         :headers,
         :rpc_options
       )
@@ -110,6 +116,8 @@ def intercept_client(next_interceptor)
         :query,
         :args,
         :reject_condition,
+        :arg_hints,
+        :result_hint,
         :headers,
         :rpc_options
       )
@@ -122,6 +130,8 @@ def intercept_client(next_interceptor)
         :update,
         :args,
         :wait_for_stage,
+        :arg_hints,
+        :result_hint,
         :headers,
         :rpc_options
       )
@@ -220,6 +230,7 @@ def intercept_client(next_interceptor)
       HeartbeatAsyncActivityInput = Data.define(
         :task_token_or_id_reference,
         :details,
+        :detail_hints,
         :rpc_options
       )
 
@@ -227,6 +238,7 @@ def intercept_client(next_interceptor)
       CompleteAsyncActivityInput = Data.define(
         :task_token_or_id_reference,
         :result,
+        :result_hint,
         :rpc_options
       )
 
@@ -235,6 +247,7 @@ def intercept_client(next_interceptor)
         :task_token_or_id_reference,
         :error,
         :last_heartbeat_details,
+        :last_heartbeat_detail_hints,
         :rpc_options
       )
 
@@ -242,6 +255,7 @@ def intercept_client(next_interceptor)
       ReportCancellationAsyncActivityInput = Data.define(
         :task_token_or_id_reference,
         :details,
+        :detail_hints,
         :rpc_options
       )
 
diff --git a/temporalio/lib/temporalio/client/schedule.rb b/temporalio/lib/temporalio/client/schedule.rb
index 95e71e04..1de6298d 100644
--- a/temporalio/lib/temporalio/client/schedule.rb
+++ b/temporalio/lib/temporalio/client/schedule.rb
@@ -175,6 +175,7 @@ def _to_proto(data_converter)
           :retry_policy,
           :memo,
           :search_attributes,
+          :arg_hints,
           :headers
         )
 
@@ -208,6 +209,9 @@ def _to_proto(data_converter)
         #   @return [Hash<String, Object>, nil] Memo for the workflow.
         # @!attribute search_attributes
         #   @return [SearchAttributes, nil] Search attributes for the workflow.
+        # @!attribute arg_hints
+        #   @return [Array<Object>, nil] Converter hints for workflow arguments. This is only user-set (e.g. on create)
+        #     and is not persisted and therefore will not be set when describing a workflow.
         # @!attribute headers
         #   @return [Hash<String, Object>, nil] Headers for the workflow.
         class StartWorkflow
@@ -249,10 +253,13 @@ def new(
               retry_policy: nil,
               memo: nil,
               search_attributes: nil,
+              arg_hints: nil,
               headers: nil
             )
+              workflow, defn_arg_hints, =
+                Workflow::Definition._workflow_type_and_hints_from_workflow_parameter(workflow)
               _original_new( # steep:ignore
-                workflow: Workflow::Definition._workflow_type_from_workflow_parameter(workflow),
+                workflow:,
                 args:,
                 id:,
                 task_queue:,
@@ -264,6 +271,7 @@ def new(
                 retry_policy:,
                 memo:,
                 search_attributes:,
+                arg_hints: arg_hints || defn_arg_hints,
                 headers:
               )
             end
@@ -296,7 +304,7 @@ def _to_proto(data_converter)
                 workflow_id: id,
                 workflow_type: Api::Common::V1::WorkflowType.new(name: workflow),
                 task_queue: Api::TaskQueue::V1::TaskQueue.new(name: task_queue),
-                input: data_converter.to_payloads(args),
+                input: data_converter.to_payloads(args, hints: arg_hints),
                 workflow_execution_timeout: Internal::ProtoUtils.seconds_to_duration(execution_timeout),
                 workflow_run_timeout: Internal::ProtoUtils.seconds_to_duration(run_timeout),
                 workflow_task_timeout: Internal::ProtoUtils.seconds_to_duration(task_timeout),
diff --git a/temporalio/lib/temporalio/client/with_start_workflow_operation.rb b/temporalio/lib/temporalio/client/with_start_workflow_operation.rb
index ef3c1b78..17743197 100644
--- a/temporalio/lib/temporalio/client/with_start_workflow_operation.rb
+++ b/temporalio/lib/temporalio/client/with_start_workflow_operation.rb
@@ -24,6 +24,8 @@ class WithStartWorkflowOperation
         :memo,
         :search_attributes,
         :start_delay,
+        :arg_hints,
+        :result_hint,
         :headers
       )
 
@@ -55,10 +57,14 @@ def initialize(
         memo: nil,
         search_attributes: nil,
         start_delay: nil,
+        arg_hints: nil,
+        result_hint: nil,
         headers: {}
       )
+        workflow, defn_arg_hints, defn_result_hint =
+          Workflow::Definition._workflow_type_and_hints_from_workflow_parameter(workflow)
         @options = Options.new(
-          workflow: Workflow::Definition._workflow_type_from_workflow_parameter(workflow),
+          workflow:,
           args:,
           id:,
           task_queue:,
@@ -74,6 +80,8 @@ def initialize(
           memo:,
           search_attributes:,
           start_delay:,
+          arg_hints: arg_hints || defn_arg_hints,
+          result_hint: result_hint || defn_result_hint,
           headers:
         )
         @workflow_handle_mutex = Mutex.new
diff --git a/temporalio/lib/temporalio/client/workflow_handle.rb b/temporalio/lib/temporalio/client/workflow_handle.rb
index 77a183f5..4fdae65f 100644
--- a/temporalio/lib/temporalio/client/workflow_handle.rb
+++ b/temporalio/lib/temporalio/client/workflow_handle.rb
@@ -48,13 +48,21 @@ class WorkflowHandle
       # @return [String, nil] First execution run ID.
       attr_reader :first_execution_run_id
 
+      # Result hint for the result of this workflow. If this handle was created via {Client.start_workflow}, this is set
+      # from there (either via result hint on that call or workflow definition's result hint). Otherwise, the result
+      # hint is set by the creator of the handle.
+      #
+      # @return [Object, nil] Result hint.
+      attr_reader :result_hint
+
       # @!visibility private
-      def initialize(client:, id:, run_id:, result_run_id:, first_execution_run_id:)
+      def initialize(client:, id:, run_id:, result_run_id:, first_execution_run_id:, result_hint:)
         @client = client
         @id = id
         @run_id = run_id
         @result_run_id = result_run_id
         @first_execution_run_id = first_execution_run_id
+        @result_hint = result_hint
       end
 
       # Wait for the result of the workflow.
@@ -64,6 +72,8 @@ def initialize(client:, id:, run_id:, result_run_id:, first_execution_run_id:)
       #
       # @param follow_runs [Boolean] If +true+, workflow runs will be continually fetched across retries and continue as
       #   new until the latest one is found. If +false+, the first result is used.
+      # @param result_hint [Object, nil] Override the result hint for the result. If unset/nil, uses one on the handle
+      #   itself.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
       #
       # @return [Object] Result of the workflow after being converted by the data converter.
@@ -71,7 +81,7 @@ def initialize(client:, id:, run_id:, result_run_id:, first_execution_run_id:)
       # @raise [Error::WorkflowFailedError] Workflow failed with +cause+ as the cause.
       # @raise [Error::WorkflowContinuedAsNewError] Workflow continued as new and +follow_runs+ is +false+.
       # @raise [Error::RPCError] RPC error from call.
-      def result(follow_runs: true, rpc_options: nil)
+      def result(follow_runs: true, result_hint: nil, rpc_options: nil)
         # Wait on the close event, following as needed
         hist_run_id = result_run_id
         loop do
@@ -91,7 +101,7 @@ def result(follow_runs: true, rpc_options: nil)
             hist_run_id = attrs.new_execution_run_id
             next if follow_runs && hist_run_id && !hist_run_id.empty?
 
-            return @client.data_converter.from_payloads(attrs.result).first
+            return @client.data_converter.from_payloads(attrs.result, hints: Array(@result_hint || result_hint)).first
           when :EVENT_TYPE_WORKFLOW_EXECUTION_FAILED
             attrs = event.workflow_execution_failed_event_attributes
             hist_run_id = attrs.new_execution_run_id
@@ -212,18 +222,22 @@ def fetch_history_events(
       #
       # @param signal [Workflow::Definition::Signal, Symbol, String] Signal definition or name.
       # @param args [Array<Object>] Signal arguments.
+      # @param arg_hints [Array<Object>, nil] Signal argument hints. If unset/nil and a signal definition is passed,
+      #   uses the ones on the signal definition if present.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
       #
       # @raise [Error::RPCError] RPC error from call.
       #
       # @note Handles created as a result of {Client.start_workflow} will signal the latest workflow with the same
       #   workflow ID even if it is unrelated to the started workflow.
-      def signal(signal, *args, rpc_options: nil)
+      def signal(signal, *args, arg_hints: nil, rpc_options: nil)
+        signal, defn_arg_hints = Workflow::Definition::Signal._name_and_hints_from_parameter(signal)
         @client._impl.signal_workflow(Interceptor::SignalWorkflowInput.new(
                                         workflow_id: id,
                                         run_id:,
-                                        signal: Workflow::Definition::Signal._name_from_parameter(signal),
+                                        signal:,
                                         args:,
+                                        arg_hints: arg_hints || defn_arg_hints,
                                         headers: {},
                                         rpc_options:
                                       ))
@@ -235,6 +249,10 @@ def signal(signal, *args, rpc_options: nil)
       # @param query [Workflow::Definition::Query, Symbol, String] Query definition or name.
       # @param args [Array<Object>] Query arguments.
       # @param reject_condition [WorkflowQueryRejectCondition, nil] Condition for rejecting the query.
+      # @param arg_hints [Array<Object>, nil] Query argument hints. If unset/nil and a query definition is passed,
+      #   uses the ones on the query definition if present.
+      # @param result_hint [Object, nil] Query result hints. If unset/nil and a query definition is passed, uses the
+      #   one on the query definition if present.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
       #
       # @return [Object, nil] Query result.
@@ -249,14 +267,19 @@ def query(
         query,
         *args,
         reject_condition: @client.options.default_workflow_query_reject_condition,
+        arg_hints: nil,
+        result_hint: nil,
         rpc_options: nil
       )
+        query, defn_arg_hints, defn_result_hint = Workflow::Definition::Query._name_and_hints_from_parameter(query)
         @client._impl.query_workflow(Interceptor::QueryWorkflowInput.new(
                                        workflow_id: id,
                                        run_id:,
-                                       query: Workflow::Definition::Query._name_from_parameter(query),
+                                       query:,
                                        args:,
                                        reject_condition:,
+                                       arg_hints: arg_hints || defn_arg_hints,
+                                       result_hint: result_hint || defn_result_hint,
                                        headers: {},
                                        rpc_options:
                                      ))
@@ -270,6 +293,10 @@ def query(
       # @param wait_for_stage [WorkflowUpdateWaitStage] Required stage to wait until returning. ADMITTED is not
       #   currently supported. See https://docs.temporal.io/workflows#update for more details.
       # @param id [String] ID of the update.
+      # @param arg_hints [Array<Object>, nil] Update argument hints. If unset/nil and am update definition is passed,
+      #   uses the ones on the update definition if present.
+      # @param result_hint [Object, nil] Update result hints. If unset/nil and an update definition is passed, uses the
+      #   one on the update definition if present.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
       #
       # @return [WorkflowUpdateHandle] The update handle.
@@ -285,15 +312,20 @@ def start_update(
         *args,
         wait_for_stage:,
         id: SecureRandom.uuid,
+        arg_hints: nil,
+        result_hint: nil,
         rpc_options: nil
       )
+        update, defn_arg_hints, defn_result_hint = Workflow::Definition::Update._name_and_hints_from_parameter(update)
         @client._impl.start_workflow_update(Interceptor::StartWorkflowUpdateInput.new(
                                               workflow_id: self.id,
                                               run_id:,
                                               update_id: id,
-                                              update: Workflow::Definition::Update._name_from_parameter(update),
+                                              update:,
                                               args:,
                                               wait_for_stage:,
+                                              arg_hints: arg_hints || defn_arg_hints,
+                                              result_hint: result_hint || defn_result_hint,
                                               headers: {},
                                               rpc_options:
                                             ))
@@ -305,6 +337,10 @@ def start_update(
       # @param update [Workflow::Definition::Update, Symbol, String] Update definition or name.
       # @param args [Array<Object>] Update arguments.
       # @param id [String] ID of the update.
+      # @param arg_hints [Array<Object>, nil] Update argument hints. If unset/nil and am update definition is passed,
+      #   uses the ones on the update definition if present.
+      # @param result_hint [Object, nil] Update result hints. If unset/nil and an update definition is passed, uses the
+      #   one on the update definition if present.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
       #
       # @return [Object, nil] Update result.
@@ -316,12 +352,14 @@ def start_update(
       #
       # @note Handles created as a result of {Client.start_workflow} will send updates the latest workflow with the same
       #   workflow ID even if it is unrelated to the started workflow.
-      def execute_update(update, *args, id: SecureRandom.uuid, rpc_options: nil)
+      def execute_update(update, *args, id: SecureRandom.uuid, arg_hints: nil, result_hint: nil, rpc_options: nil)
         start_update(
           update,
           *args,
           wait_for_stage: WorkflowUpdateWaitStage::COMPLETED,
           id:,
+          arg_hints:,
+          result_hint:,
           rpc_options:
         ).result
       end
@@ -331,15 +369,17 @@ def execute_update(update, *args, id: SecureRandom.uuid, rpc_options: nil)
       # @param id [String] ID of the update.
       # @param specific_run_id [String, nil] Workflow run ID to get update handle for. Default is the {run_id}. Most
       #   users will not need to set this and instead use the one on the class.
+      # @param result_hint [Object, nil] Result hint for the update result to set on the handle.
       #
       # @return [WorkflowUpdateHandle] The update handle.
-      def update_handle(id, specific_run_id: run_id)
+      def update_handle(id, specific_run_id: run_id, result_hint: nil)
         WorkflowUpdateHandle.new(
           client: @client,
           id:,
           workflow_id: self.id,
           workflow_run_id: specific_run_id,
-          known_outcome: nil
+          known_outcome: nil,
+          result_hint:
         )
       end
 
diff --git a/temporalio/lib/temporalio/client/workflow_update_handle.rb b/temporalio/lib/temporalio/client/workflow_update_handle.rb
index 7d48f7cb..c59bb2bf 100644
--- a/temporalio/lib/temporalio/client/workflow_update_handle.rb
+++ b/temporalio/lib/temporalio/client/workflow_update_handle.rb
@@ -18,13 +18,17 @@ class WorkflowUpdateHandle
       # @return [String, nil] Run ID for the workflow.
       attr_reader :workflow_run_id
 
+      # @return [Object, nil] Result hint if one set when the handle was created.
+      attr_reader :result_hint
+
       # @!visibility private
-      def initialize(client:, id:, workflow_id:, workflow_run_id:, known_outcome:)
+      def initialize(client:, id:, workflow_id:, workflow_run_id:, known_outcome:, result_hint:)
         @client = client
         @id = id
         @workflow_id = workflow_id
         @workflow_run_id = workflow_run_id
         @known_outcome = known_outcome
+        @result_hint = result_hint
       end
 
       # @return [Boolean] True if the result is already known and {result} will not make a blocking call, false if
@@ -36,6 +40,7 @@ def result_obtained?
       # Wait for and return the result of the update. The result may already be known in which case no network call is
       # made. Otherwise the result will be polled for until it is returned.
       #
+      # @param result_hint [Object, nil] If not nil, overrides handle-level result hint for getting the result.
       # @param rpc_options [RPCOptions, nil] Advanced RPC options.
       #
       # @return [Object, nil] Update result.
@@ -44,7 +49,7 @@ def result_obtained?
       # @raise [Error::WorkflowUpdateRPCTimeoutOrCanceledError] This update call timed out or was canceled. This doesn't
       #   mean the update itself was timed out or canceled.
       # @raise [Error::RPCError] RPC error from call.
-      def result(rpc_options: nil)
+      def result(result_hint: nil, rpc_options: nil)
         @known_outcome ||= @client._impl.poll_workflow_update(Interceptor::PollWorkflowUpdateInput.new(
                                                                 workflow_id:,
                                                                 run_id: workflow_run_id,
@@ -56,7 +61,8 @@ def result(rpc_options: nil)
           raise Error::WorkflowUpdateFailedError.new, cause: @client.data_converter.from_failure(@known_outcome.failure)
         end
 
-        results = @client.data_converter.from_payloads(@known_outcome.success)
+        results = @client.data_converter.from_payloads(@known_outcome.success,
+                                                       hints: Array(result_hint || @result_hint))
         warn("Expected 0 or 1 update result, got #{results.size}") if results.size > 1
         results.first
       end
diff --git a/temporalio/lib/temporalio/converters/data_converter.rb b/temporalio/lib/temporalio/converters/data_converter.rb
index f518ac7e..72e7ccf3 100644
--- a/temporalio/lib/temporalio/converters/data_converter.rb
+++ b/temporalio/lib/temporalio/converters/data_converter.rb
@@ -40,9 +40,10 @@ def initialize(
       # Convert a Ruby value to a payload and encode it.
       #
       # @param value [Object] Ruby value.
+      # @param hint [Object, nil] Hint, if any, to assist conversion.
       # @return [Api::Common::V1::Payload] Converted and encoded payload.
-      def to_payload(value)
-        payload = payload_converter.to_payload(value)
+      def to_payload(value, hint: nil)
+        payload = payload_converter.to_payload(value, hint:)
         payload = payload_codec.encode([payload]).first if payload_codec
         payload
       end
@@ -50,9 +51,13 @@ def to_payload(value)
       # Convert multiple Ruby values to a payload set and encode it.
       #
       # @param values [Object] Ruby values, converted to array via {::Array}.
+      # @param hints [Array<Object>, nil] Hints, if any, to assist conversion. Note, when using the default converter
+      #   that converts a payload at a time, hints for each value are taken from the array at that value's index. So if
+      #   there are fewer hints than values, some values will not have a hint. Similarly if there are more hints than
+      #   values, the trailing hints are not used.
       # @return [Api::Common::V1::Payloads] Converted and encoded payload set.
-      def to_payloads(values)
-        payloads = payload_converter.to_payloads(values)
+      def to_payloads(values, hints: nil)
+        payloads = payload_converter.to_payloads(values, hints:)
         payloads.payloads.replace(payload_codec.encode(payloads.payloads)) if payload_codec && !payloads.payloads.empty?
         payloads
       end
@@ -60,23 +65,28 @@ def to_payloads(values)
       # Decode and convert a payload to a Ruby value.
       #
       # @param payload [Api::Common::V1::Payload] Encoded payload.
+      # @param hint [Object, nil] Hint, if any, to assist conversion.
       # @return [Object] Decoded and converted Ruby value.
-      def from_payload(payload)
+      def from_payload(payload, hint: nil)
         payload = payload_codec.decode([payload]).first if payload_codec
-        payload_converter.from_payload(payload)
+        payload_converter.from_payload(payload, hint:)
       end
 
       # Decode and convert a payload set to Ruby values.
       #
       # @param payloads [Api::Common::V1::Payloads, nil] Encoded payload set.
+      # @param hints [Array<Object>, nil] Hints, if any, to assist conversion. Note, when using the default converter
+      #   that converts a value at a time, hints for each payload are taken from the array at that payload's index. So
+      #   if there are fewer hints than payloads, some payloads will not have a hint. Similarly if there are more hints
+      #   than payloads, the trailing hints are not used.
       # @return [Array<Object>] Decoded and converted Ruby values.
-      def from_payloads(payloads)
+      def from_payloads(payloads, hints: nil)
         return [] unless payloads && !payloads.payloads.empty?
 
         if payload_codec && !payloads.payloads.empty?
           payloads = Api::Common::V1::Payloads.new(payloads: payload_codec.decode(payloads.payloads))
         end
-        payload_converter.from_payloads(payloads)
+        payload_converter.from_payloads(payloads, hints:)
       end
 
       # Convert a Ruby error to a Temporal failure and encode it.
diff --git a/temporalio/lib/temporalio/converters/payload_converter.rb b/temporalio/lib/temporalio/converters/payload_converter.rb
index 81c680ec..ed305326 100644
--- a/temporalio/lib/temporalio/converters/payload_converter.rb
+++ b/temporalio/lib/temporalio/converters/payload_converter.rb
@@ -34,37 +34,47 @@ def self.new_with_defaults(json_parse_options: { create_additions: true }, json_
       # Convert a Ruby value to a payload.
       #
       # @param value [Object] Ruby value.
+      # @param hint [Object, nil] Hint, if any, to assist conversion.
       # @return [Api::Common::V1::Payload] Converted payload.
-      def to_payload(value)
+      def to_payload(value, hint: nil)
         raise NotImplementedError
       end
 
       # Convert multiple Ruby values to a payload set.
       #
       # @param values [Object] Ruby values, converted to array via {::Array}.
+      # @param hints [Array<Object>, nil] Hints, if any, to assist conversion. Note, when using the default converter
+      #   that converts a payload at a time, hints for each value are taken from the array at that value's index. So if
+      #   there are fewer hints than values, some values will not have a hint. Similarly if there are more hints than
+      #   values, the trailing hints are not used.
       # @return [Api::Common::V1::Payloads] Converted payload set.
-      def to_payloads(values)
+      def to_payloads(values, hints: nil)
         Api::Common::V1::Payloads.new(
-          payloads: Array(values).map { |value| to_payload(value) }
+          payloads: Array(values).zip(Array(hints)).map { |value, hint| to_payload(value, hint:) }
         )
       end
 
       # Convert a payload to a Ruby value.
       #
       # @param payload [Api::Common::V1::Payload] Payload.
+      # @param hint [Object, nil] Hint, if any, to assist conversion.
       # @return [Object] Converted Ruby value.
-      def from_payload(payload)
+      def from_payload(payload, hint: nil)
         raise NotImplementedError
       end
 
       # Convert a payload set to Ruby values.
       #
       # @param payloads [Api::Common::V1::Payloads, nil] Payload set.
+      # @param hints [Array<Object>, nil] Hints, if any, to assist conversion. Note, when using the default converter
+      #   that converts a value at a time, hints for each payload are taken from the array at that payload's index. So
+      #   if there are fewer hints than payloads, some payloads will not have a hint. Similarly if there are more hints
+      #   than payloads, the trailing hints are not used.
       # @return [Array<Object>] Converted Ruby values.
-      def from_payloads(payloads)
+      def from_payloads(payloads, hints: nil)
         return [] unless payloads
 
-        payloads.payloads.map { |payload| from_payload(payload) }
+        payloads.payloads.zip(Array(hints)).map { |payload, hint| from_payload(payload, hint:) }
       end
     end
   end
diff --git a/temporalio/lib/temporalio/converters/payload_converter/binary_null.rb b/temporalio/lib/temporalio/converters/payload_converter/binary_null.rb
index 304bddb4..5459df43 100644
--- a/temporalio/lib/temporalio/converters/payload_converter/binary_null.rb
+++ b/temporalio/lib/temporalio/converters/payload_converter/binary_null.rb
@@ -16,7 +16,7 @@ def encoding
         end
 
         # (see Encoding.to_payload)
-        def to_payload(value)
+        def to_payload(value, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           return nil unless value.nil?
 
           Api::Common::V1::Payload.new(
@@ -25,7 +25,7 @@ def to_payload(value)
         end
 
         # (see Encoding.from_payload)
-        def from_payload(payload) # rubocop:disable Lint/UnusedMethodArgument
+        def from_payload(payload, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           nil
         end
       end
diff --git a/temporalio/lib/temporalio/converters/payload_converter/binary_plain.rb b/temporalio/lib/temporalio/converters/payload_converter/binary_plain.rb
index c6f77296..076d38e0 100644
--- a/temporalio/lib/temporalio/converters/payload_converter/binary_plain.rb
+++ b/temporalio/lib/temporalio/converters/payload_converter/binary_plain.rb
@@ -16,7 +16,7 @@ def encoding
         end
 
         # (see Encoding.to_payload)
-        def to_payload(value)
+        def to_payload(value, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           return nil unless value.is_a?(String) && value.encoding == ::Encoding::ASCII_8BIT
 
           Temporalio::Api::Common::V1::Payload.new(
@@ -26,7 +26,7 @@ def to_payload(value)
         end
 
         # (see Encoding.from_payload)
-        def from_payload(payload)
+        def from_payload(payload, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           payload.data
         end
       end
diff --git a/temporalio/lib/temporalio/converters/payload_converter/binary_protobuf.rb b/temporalio/lib/temporalio/converters/payload_converter/binary_protobuf.rb
index 6061134b..e13f894b 100644
--- a/temporalio/lib/temporalio/converters/payload_converter/binary_protobuf.rb
+++ b/temporalio/lib/temporalio/converters/payload_converter/binary_protobuf.rb
@@ -17,7 +17,7 @@ def encoding
         end
 
         # (see Encoding.to_payload)
-        def to_payload(value)
+        def to_payload(value, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           return nil unless value.is_a?(Google::Protobuf::MessageExts)
 
           # @type var value: Google::Protobuf::MessageExts
@@ -28,7 +28,7 @@ def to_payload(value)
         end
 
         # (see Encoding.from_payload)
-        def from_payload(payload)
+        def from_payload(payload, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           type = payload.metadata['messageType']
           # @type var desc: untyped
           desc = Google::Protobuf::DescriptorPool.generated_pool.lookup(type)
diff --git a/temporalio/lib/temporalio/converters/payload_converter/composite.rb b/temporalio/lib/temporalio/converters/payload_converter/composite.rb
index d5cadabe..d81f8cab 100644
--- a/temporalio/lib/temporalio/converters/payload_converter/composite.rb
+++ b/temporalio/lib/temporalio/converters/payload_converter/composite.rb
@@ -32,14 +32,15 @@ def initialize(*converters)
         # Convert Ruby value to a payload by going over each encoding converter in order until one can convert.
         #
         # @param value [Object] Ruby value to convert.
+        # @param hint [Object, nil] Hint, if any, to assist conversion.
         # @return [Api::Common::V1::Payload] Converted payload.
         # @raise [ConverterNotFound] If no converters can process the value.
-        def to_payload(value)
+        def to_payload(value, hint: nil)
           # As a special case, raw values just return the payload within
           return value.payload if value.is_a?(RawValue)
 
           converters.each_value do |converter|
-            payload = converter.to_payload(value)
+            payload = converter.to_payload(value, hint:)
             return payload unless payload.nil?
           end
           raise ConverterNotFound, "Value of type #{value} has no known converter"
@@ -48,17 +49,18 @@ def to_payload(value)
         # Convert payload to Ruby value based on its +encoding+ metadata on the payload.
         #
         # @param payload [Api::Common::V1::Payload] Payload to convert.
+        # @param hint [Object, nil] Hint, if any, to assist conversion.
         # @return [Object] Converted Ruby value.
         # @raise [EncodingNotSet] If encoding not set on the metadata.
         # @raise [ConverterNotFound] If no converter found for the encoding.
-        def from_payload(payload)
+        def from_payload(payload, hint: nil)
           encoding = payload.metadata['encoding']
           raise EncodingNotSet, 'Missing payload encoding' unless encoding
 
           converter = converters[encoding]
           raise ConverterNotFound, "No converter for encoding #{encoding}" unless converter
 
-          converter.from_payload(payload)
+          converter.from_payload(payload, hint:)
         end
       end
     end
diff --git a/temporalio/lib/temporalio/converters/payload_converter/encoding.rb b/temporalio/lib/temporalio/converters/payload_converter/encoding.rb
index 55ab5398..36c6e7ca 100644
--- a/temporalio/lib/temporalio/converters/payload_converter/encoding.rb
+++ b/temporalio/lib/temporalio/converters/payload_converter/encoding.rb
@@ -16,8 +16,9 @@ def encoding
         # handle it, the resulting payload must have +encoding+ metadata on the payload set to the value of {encoding}.
         #
         # @param value [Object] Ruby value to possibly convert.
+        # @param hint [Object, nil] Hint, if any, to assist conversion.
         # @return [Api::Common::V1::Payload, nil] Converted payload if it can handle it, +nil+ otherwise.
-        def to_payload(value)
+        def to_payload(value, hint: nil)
           raise NotImplementedError
         end
 
@@ -25,8 +26,9 @@ def to_payload(value)
         # will error if it cannot convert.
         #
         # @param payload [Api::Common::V1::Payload] Payload to convert.
+        # @param hint [Object, nil] Hint, if any, to assist conversion.
         # @return [Object] Converted Ruby value.
-        def from_payload(payload)
+        def from_payload(payload, hint: nil)
           raise NotImplementedError
         end
       end
diff --git a/temporalio/lib/temporalio/converters/payload_converter/json_plain.rb b/temporalio/lib/temporalio/converters/payload_converter/json_plain.rb
index 14ed58a1..f71e10e2 100644
--- a/temporalio/lib/temporalio/converters/payload_converter/json_plain.rb
+++ b/temporalio/lib/temporalio/converters/payload_converter/json_plain.rb
@@ -27,7 +27,7 @@ def encoding
         end
 
         # (see Encoding.to_payload)
-        def to_payload(value)
+        def to_payload(value, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           Api::Common::V1::Payload.new(
             metadata: { 'encoding' => ENCODING },
             data: JSON.generate(value, @generate_options).b
@@ -35,7 +35,7 @@ def to_payload(value)
         end
 
         # (see Encoding.from_payload)
-        def from_payload(payload)
+        def from_payload(payload, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           JSON.parse(payload.data, @parse_options)
         end
       end
diff --git a/temporalio/lib/temporalio/converters/payload_converter/json_protobuf.rb b/temporalio/lib/temporalio/converters/payload_converter/json_protobuf.rb
index 96e7f31a..897b7c79 100644
--- a/temporalio/lib/temporalio/converters/payload_converter/json_protobuf.rb
+++ b/temporalio/lib/temporalio/converters/payload_converter/json_protobuf.rb
@@ -17,7 +17,7 @@ def encoding
         end
 
         # (see Encoding.to_payload)
-        def to_payload(value)
+        def to_payload(value, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           return nil unless value.is_a?(Google::Protobuf::MessageExts)
 
           Api::Common::V1::Payload.new(
@@ -27,7 +27,7 @@ def to_payload(value)
         end
 
         # (see Encoding.from_payload)
-        def from_payload(payload)
+        def from_payload(payload, hint: nil) # rubocop:disable Lint/UnusedMethodArgument
           type = payload.metadata['messageType']
           # @type var desc: untyped
           desc = Google::Protobuf::DescriptorPool.generated_pool.lookup(type)
diff --git a/temporalio/lib/temporalio/internal/client/implementation.rb b/temporalio/lib/temporalio/internal/client/implementation.rb
index 8f5bc12c..8466d9b0 100644
--- a/temporalio/lib/temporalio/internal/client/implementation.rb
+++ b/temporalio/lib/temporalio/internal/client/implementation.rb
@@ -53,7 +53,7 @@ def start_workflow(input)
             workflow_type: Api::Common::V1::WorkflowType.new(name: input.workflow),
             workflow_id: input.workflow_id,
             task_queue: Api::TaskQueue::V1::TaskQueue.new(name: input.task_queue.to_s),
-            input: @client.data_converter.to_payloads(input.args),
+            input: @client.data_converter.to_payloads(input.args, hints: input.arg_hints),
             workflow_execution_timeout: ProtoUtils.seconds_to_duration(input.execution_timeout),
             workflow_run_timeout: ProtoUtils.seconds_to_duration(input.run_timeout),
             workflow_task_timeout: ProtoUtils.seconds_to_duration(input.task_timeout),
@@ -103,7 +103,8 @@ def start_workflow(input)
             id: input.workflow_id,
             run_id: nil,
             result_run_id: resp.run_id,
-            first_execution_run_id: resp.run_id
+            first_execution_run_id: resp.run_id,
+            result_hint: input.result_hint
           )
         end
 
@@ -139,7 +140,7 @@ def start_update_with_start_workflow(input)
                     ),
                     input: Api::Update::V1::Input.new(
                       name: input.update,
-                      args: @client.data_converter.to_payloads(input.args),
+                      args: @client.data_converter.to_payloads(input.args, hints: input.arg_hints),
                       header: Internal::ProtoUtils.headers_to_proto(input.headers, @client.data_converter)
                     )
                   ),
@@ -169,7 +170,8 @@ def start_update_with_start_workflow(input)
                   id: start_options.id,
                   run_id: nil,
                   result_run_id: run_id,
-                  first_execution_run_id: run_id
+                  first_execution_run_id: run_id,
+                  result_hint: start_options.result_hint
                 )
               )
               update_resp = resp.responses.last.update_workflow
@@ -245,7 +247,8 @@ def start_update_with_start_workflow(input)
             id: input.update_id,
             workflow_id: start_options.id,
             workflow_run_id: run_id,
-            known_outcome: update_resp.outcome
+            known_outcome: update_resp.outcome,
+            result_hint: input.result_hint
           )
         end
 
@@ -261,7 +264,7 @@ def signal_with_start_workflow(input)
             Api::WorkflowService::V1::SignalWithStartWorkflowExecutionRequest, start_options
           )
           req.signal_name = input.signal
-          req.signal_input = @client.data_converter.to_payloads(input.args)
+          req.signal_input = @client.data_converter.to_payloads(input.args, hints: input.arg_hints)
 
           # Send request
           begin
@@ -294,7 +297,8 @@ def signal_with_start_workflow(input)
             id: start_options.id,
             run_id: nil,
             result_run_id: resp.run_id,
-            first_execution_run_id: resp.run_id
+            first_execution_run_id: resp.run_id,
+            result_hint: start_options.result_hint
           )
           input.start_workflow_operation._set_workflow_handle(handle)
           handle
@@ -307,7 +311,7 @@ def _start_workflow_request_from_with_start_options(klass, start_options)
             workflow_type: Api::Common::V1::WorkflowType.new(name: start_options.workflow),
             workflow_id: start_options.id,
             task_queue: Api::TaskQueue::V1::TaskQueue.new(name: start_options.task_queue.to_s),
-            input: @client.data_converter.to_payloads(start_options.args),
+            input: @client.data_converter.to_payloads(start_options.args, hints: start_options.arg_hints),
             workflow_execution_timeout: ProtoUtils.seconds_to_duration(start_options.execution_timeout),
             workflow_run_timeout: ProtoUtils.seconds_to_duration(start_options.run_timeout),
             workflow_task_timeout: ProtoUtils.seconds_to_duration(start_options.task_timeout),
@@ -413,7 +417,7 @@ def signal_workflow(input)
                 run_id: input.run_id || ''
               ),
               signal_name: input.signal,
-              input: @client.data_converter.to_payloads(input.args),
+              input: @client.data_converter.to_payloads(input.args, hints: input.arg_hints),
               header: Internal::ProtoUtils.headers_to_proto(input.headers, @client.data_converter),
               identity: @client.connection.identity,
               request_id: SecureRandom.uuid
@@ -434,7 +438,7 @@ def query_workflow(input)
                 ),
                 query: Api::Query::V1::WorkflowQuery.new(
                   query_type: input.query,
-                  query_args: @client.data_converter.to_payloads(input.args),
+                  query_args: @client.data_converter.to_payloads(input.args, hints: input.arg_hints),
                   header: Internal::ProtoUtils.headers_to_proto(input.headers, @client.data_converter)
                 ),
                 query_reject_condition: input.reject_condition || 0
@@ -454,7 +458,7 @@ def query_workflow(input)
             ))
           end
 
-          results = @client.data_converter.from_payloads(resp.query_result)
+          results = @client.data_converter.from_payloads(resp.query_result, hints: Array(input.result_hint))
           warn("Expected 0 or 1 query result, got #{results.size}") if results.size > 1
           results&.first
         end
@@ -477,7 +481,7 @@ def start_workflow_update(input)
               ),
               input: Api::Update::V1::Input.new(
                 name: input.update,
-                args: @client.data_converter.to_payloads(input.args),
+                args: @client.data_converter.to_payloads(input.args, hints: input.arg_hints),
                 header: Internal::ProtoUtils.headers_to_proto(input.headers, @client.data_converter)
               )
             ),
@@ -534,7 +538,8 @@ def start_workflow_update(input)
             id: input.update_id,
             workflow_id: input.workflow_id,
             workflow_run_id: input.run_id,
-            known_outcome: resp.outcome
+            known_outcome: resp.outcome,
+            result_hint: input.result_hint
           )
         end
 
@@ -809,7 +814,7 @@ def heartbeat_async_activity(input)
                        activity_id: input.task_token_or_id_reference.activity_id,
                        namespace: @client.namespace,
                        identity: @client.connection.identity,
-                       details: @client.data_converter.to_payloads(input.details)
+                       details: @client.data_converter.to_payloads(input.details, hints: input.detail_hints)
                      ),
                      rpc_options: Implementation.with_default_rpc_options(input.rpc_options)
                    )
@@ -819,7 +824,7 @@ def heartbeat_async_activity(input)
                        task_token: input.task_token_or_id_reference,
                        namespace: @client.namespace,
                        identity: @client.connection.identity,
-                       details: @client.data_converter.to_payloads(input.details)
+                       details: @client.data_converter.to_payloads(input.details, hints: input.detail_hints)
                      ),
                      rpc_options: Implementation.with_default_rpc_options(input.rpc_options)
                    )
@@ -838,7 +843,7 @@ def complete_async_activity(input)
                 activity_id: input.task_token_or_id_reference.activity_id,
                 namespace: @client.namespace,
                 identity: @client.connection.identity,
-                result: @client.data_converter.to_payloads([input.result])
+                result: @client.data_converter.to_payloads([input.result], hints: Array(input.result_hint))
               ),
               rpc_options: Implementation.with_default_rpc_options(input.rpc_options)
             )
@@ -848,7 +853,7 @@ def complete_async_activity(input)
                 task_token: input.task_token_or_id_reference,
                 namespace: @client.namespace,
                 identity: @client.connection.identity,
-                result: @client.data_converter.to_payloads([input.result])
+                result: @client.data_converter.to_payloads([input.result], hints: Array(input.result_hint))
               ),
               rpc_options: Implementation.with_default_rpc_options(input.rpc_options)
             )
@@ -857,6 +862,14 @@ def complete_async_activity(input)
         end
 
         def fail_async_activity(input)
+          last_heartbeat_details = if input.last_heartbeat_details.empty?
+                                     nil
+                                   else
+                                     @client.data_converter.to_payloads(
+                                       input.last_heartbeat_details,
+                                       hints: input.last_heartbeat_detail_hints
+                                     )
+                                   end
           if input.task_token_or_id_reference.is_a?(Temporalio::Client::ActivityIDReference)
             @client.workflow_service.respond_activity_task_failed_by_id(
               Api::WorkflowService::V1::RespondActivityTaskFailedByIdRequest.new(
@@ -866,11 +879,7 @@ def fail_async_activity(input)
                 namespace: @client.namespace,
                 identity: @client.connection.identity,
                 failure: @client.data_converter.to_failure(input.error),
-                last_heartbeat_details: if input.last_heartbeat_details.empty?
-                                          nil
-                                        else
-                                          @client.data_converter.to_payloads(input.last_heartbeat_details)
-                                        end
+                last_heartbeat_details:
               ),
               rpc_options: Implementation.with_default_rpc_options(input.rpc_options)
             )
@@ -881,11 +890,7 @@ def fail_async_activity(input)
                 namespace: @client.namespace,
                 identity: @client.connection.identity,
                 failure: @client.data_converter.to_failure(input.error),
-                last_heartbeat_details: if input.last_heartbeat_details.empty?
-                                          nil
-                                        else
-                                          @client.data_converter.to_payloads(input.last_heartbeat_details)
-                                        end
+                last_heartbeat_details:
               ),
               rpc_options: Implementation.with_default_rpc_options(input.rpc_options)
             )
@@ -902,7 +907,7 @@ def report_cancellation_async_activity(input)
                 activity_id: input.task_token_or_id_reference.activity_id,
                 namespace: @client.namespace,
                 identity: @client.connection.identity,
-                details: @client.data_converter.to_payloads(input.details)
+                details: @client.data_converter.to_payloads(input.details, hints: input.detail_hints)
               ),
               rpc_options: Implementation.with_default_rpc_options(input.rpc_options)
             )
@@ -912,7 +917,7 @@ def report_cancellation_async_activity(input)
                 task_token: input.task_token_or_id_reference,
                 namespace: @client.namespace,
                 identity: @client.connection.identity,
-                details: @client.data_converter.to_payloads(input.details)
+                details: @client.data_converter.to_payloads(input.details, hints: input.detail_hints)
               ),
               rpc_options: Implementation.with_default_rpc_options(input.rpc_options)
             )
diff --git a/temporalio/lib/temporalio/internal/proto_utils.rb b/temporalio/lib/temporalio/internal/proto_utils.rb
index 6ebfa33c..e94a4b7d 100644
--- a/temporalio/lib/temporalio/internal/proto_utils.rb
+++ b/temporalio/lib/temporalio/internal/proto_utils.rb
@@ -94,16 +94,16 @@ def self.enum_to_int(enum_mod, enum_val, zero_means_nil: false)
         enum_val
       end
 
-      def self.convert_from_payload_array(converter, payloads)
+      def self.convert_from_payload_array(converter, payloads, hints:)
         return [] if payloads.empty?
 
-        converter.from_payloads(Api::Common::V1::Payloads.new(payloads:))
+        converter.from_payloads(Api::Common::V1::Payloads.new(payloads:), hints:)
       end
 
-      def self.convert_to_payload_array(converter, values)
+      def self.convert_to_payload_array(converter, values, hints:)
         return [] if values.empty?
 
-        converter.to_payloads(values).payloads.to_ary
+        converter.to_payloads(values, hints:).payloads.to_ary
       end
 
       def self.assert_non_reserved_name(name)
diff --git a/temporalio/lib/temporalio/internal/worker/activity_worker.rb b/temporalio/lib/temporalio/internal/worker/activity_worker.rb
index 89a8be77..7c1bf7e8 100644
--- a/temporalio/lib/temporalio/internal/worker/activity_worker.rb
+++ b/temporalio/lib/temporalio/internal/worker/activity_worker.rb
@@ -178,7 +178,8 @@ def execute_activity(task_token, defn, start)
             ) || raise, # Never nil
             heartbeat_details: ProtoUtils.convert_from_payload_array(
               @worker.options.client.data_converter,
-              start.heartbeat_details.to_ary
+              start.heartbeat_details.to_ary,
+              hints: nil
             ),
             heartbeat_timeout: Internal::ProtoUtils.duration_to_seconds(start.heartbeat_timeout),
             local?: start.is_local,
@@ -205,8 +206,13 @@ def execute_activity(task_token, defn, start)
                     payloads = codec.decode(payloads) if codec
                     payloads.map { |p| Temporalio::Converters::RawValue.new(p) }
                   else
-                    ProtoUtils.convert_from_payload_array(@worker.options.client.data_converter, start.input.to_ary)
+                    ProtoUtils.convert_from_payload_array(
+                      @worker.options.client.data_converter,
+                      start.input.to_ary,
+                      hints: defn.arg_hints
+                    )
                   end,
+            result_hint: defn.result_hint,
             headers: ProtoUtils.headers_from_proto_map(start.header_fields, @worker.options.client.data_converter) || {}
           )
 
@@ -267,7 +273,7 @@ def run_activity(defn, activity, input)
             # Success
             Bridge::Api::ActivityResult::ActivityExecutionResult.new(
               completed: Bridge::Api::ActivityResult::Success.new(
-                result: @worker.options.client.data_converter.to_payload(result)
+                result: @worker.options.client.data_converter.to_payload(result, hint: input.result_hint)
               )
             )
           rescue Exception => e # rubocop:disable Lint/RescueException -- We are intending to catch everything here
@@ -372,13 +378,15 @@ def initialize( # rubocop:disable Lint/MissingSuper
             @_server_requested_cancel = false
           end
 
-          def heartbeat(*details)
+          def heartbeat(*details, detail_hints: nil)
             raise 'Implementation not set yet' if _outbound_impl.nil?
 
             # No-op if local
             return if info.local?
 
-            _outbound_impl.heartbeat(Temporalio::Worker::Interceptor::Activity::HeartbeatInput.new(details:))
+            _outbound_impl.heartbeat(
+              Temporalio::Worker::Interceptor::Activity::HeartbeatInput.new(details:, detail_hints:)
+            )
           end
 
           def metric_meter
@@ -437,7 +445,8 @@ def heartbeat(input)
               Bridge::Api::CoreInterface::ActivityHeartbeat.new(
                 task_token: @task_token,
                 details: ProtoUtils.convert_to_payload_array(@worker.worker.options.client.data_converter,
-                                                             input.details)
+                                                             input.details,
+                                                             hints: input.detail_hints)
               ).to_proto
             )
           end
diff --git a/temporalio/lib/temporalio/internal/worker/workflow_instance.rb b/temporalio/lib/temporalio/internal/worker/workflow_instance.rb
index 1c9dad3f..6ec101e4 100644
--- a/temporalio/lib/temporalio/internal/worker/workflow_instance.rb
+++ b/temporalio/lib/temporalio/internal/worker/workflow_instance.rb
@@ -312,7 +312,8 @@ def create_instance
           # Convert workflow arguments
           @workflow_arguments = convert_args(payload_array: @init_job.arguments,
                                              method_name: :execute,
-                                             raw_args: @definition.raw_args)
+                                             raw_args: @definition.raw_args,
+                                             arg_hints: @definition.arg_hints)
 
           # Initialize interceptors
           @inbound = @interceptors.reverse_each.reduce(InboundImplementation.new(self)) do |acc, int|
@@ -420,6 +421,7 @@ def apply_signal(job)
         end
 
         def apply_query(job)
+          result_hint = nil
           schedule do
             # If it's a built-in, run it without interceptors, otherwise do normal behavior
             result = if job.query_type == '__stack_trace'
@@ -437,6 +439,7 @@ def apply_query(job)
                          raise "Query handler for #{job.query_type} expected but not found, " \
                                "known queries: [#{query_handlers.keys.compact.sort.join(', ')}]"
                        end
+                       result_hint = defn.result_hint
 
                        with_context_frozen do
                          @inbound.handle_query(
@@ -460,7 +463,7 @@ def apply_query(job)
                 respond_to_query: Bridge::Api::WorkflowCommands::QueryResult.new(
                   query_id: job.query_id,
                   succeeded: Bridge::Api::WorkflowCommands::QuerySuccess.new(
-                    response: @payload_converter.to_payload(result)
+                    response: @payload_converter.to_payload(result, hint: result_hint)
                   )
                 )
               )
@@ -549,7 +552,7 @@ def apply_update(job)
               Bridge::Api::WorkflowCommands::WorkflowCommand.new(
                 update_response: Bridge::Api::WorkflowCommands::UpdateResponse.new(
                   protocol_instance_id: job.protocol_instance_id,
-                  completed: @payload_converter.to_payload(result)
+                  completed: @payload_converter.to_payload(result, hint: defn.result_hint)
                 )
               )
             )
@@ -579,7 +582,7 @@ def run_workflow
           add_command(
             Bridge::Api::WorkflowCommands::WorkflowCommand.new(
               complete_workflow_execution: Bridge::Api::WorkflowCommands::CompleteWorkflowExecution.new(
-                result: @payload_converter.to_payload(result)
+                result: @payload_converter.to_payload(result, hint: @definition.result_hint)
               )
             )
           )
@@ -607,14 +610,19 @@ def schedule(
         def on_top_level_exception(err)
           if err.is_a?(Workflow::ContinueAsNewError)
             @logger.debug('Workflow requested continue as new')
+            workflow_type, defn_arg_hints, =
+              if err.workflow
+                Workflow::Definition._workflow_type_and_hints_from_workflow_parameter(err.workflow)
+              else
+                [nil, @definition.arg_hints, nil]
+              end
             add_command(
               Bridge::Api::WorkflowCommands::WorkflowCommand.new(
                 continue_as_new_workflow_execution: Bridge::Api::WorkflowCommands::ContinueAsNewWorkflowExecution.new(
-                  workflow_type: if err.workflow
-                                   Workflow::Definition._workflow_type_from_workflow_parameter(err.workflow)
-                                 end,
+                  workflow_type:,
                   task_queue: err.task_queue,
-                  arguments: ProtoUtils.convert_to_payload_array(payload_converter, err.args),
+                  arguments: ProtoUtils.convert_to_payload_array(payload_converter, err.args,
+                                                                 hints: err.arg_hints || defn_arg_hints),
                   workflow_run_timeout: ProtoUtils.seconds_to_duration(err.run_timeout),
                   workflow_task_timeout: ProtoUtils.seconds_to_duration(err.task_timeout),
                   memo: ProtoUtils.memo_to_proto_hash(err.memo, payload_converter),
@@ -669,11 +677,12 @@ def convert_handler_args(payload_array:, defn:)
             payload_array:,
             method_name: defn.to_invoke.is_a?(Symbol) ? defn.to_invoke : nil,
             raw_args: defn.raw_args,
+            arg_hints: defn.arg_hints,
             ignore_first_param: defn.name.nil? # Dynamic
           )
         end
 
-        def convert_args(payload_array:, method_name:, raw_args:, ignore_first_param: false)
+        def convert_args(payload_array:, method_name:, raw_args:, arg_hints:, ignore_first_param: false)
           # Just in case it is not an array
           payload_array = payload_array.to_ary
 
@@ -713,7 +722,7 @@ def convert_args(payload_array:, method_name:, raw_args:, ignore_first_param: fa
           if raw_args
             payload_array.map { |p| Converters::RawValue.new(p) }
           else
-            ProtoUtils.convert_from_payload_array(@payload_converter, payload_array)
+            ProtoUtils.convert_from_payload_array(@payload_converter, payload_array, hints: arg_hints)
           end
         end
 
diff --git a/temporalio/lib/temporalio/internal/worker/workflow_instance/child_workflow_handle.rb b/temporalio/lib/temporalio/internal/worker/workflow_instance/child_workflow_handle.rb
index e6c5656e..1a0a0e3c 100644
--- a/temporalio/lib/temporalio/internal/worker/workflow_instance/child_workflow_handle.rb
+++ b/temporalio/lib/temporalio/internal/worker/workflow_instance/child_workflow_handle.rb
@@ -10,18 +10,20 @@ module Worker
       class WorkflowInstance
         # Implementation of the child workflow handle.
         class ChildWorkflowHandle < Workflow::ChildWorkflowHandle
-          attr_reader :id, :first_execution_run_id
+          attr_reader :id, :first_execution_run_id, :result_hint
 
-          def initialize(id:, first_execution_run_id:, instance:, cancellation:, cancel_callback_key:) # rubocop:disable Lint/MissingSuper
+          def initialize(id:, first_execution_run_id:, instance:, # rubocop:disable Lint/MissingSuper
+                         cancellation:, cancel_callback_key:, result_hint:)
             @id = id
             @first_execution_run_id = first_execution_run_id
             @instance = instance
             @cancellation = cancellation
             @cancel_callback_key = cancel_callback_key
+            @result_hint = result_hint
             @resolution = nil
           end
 
-          def result
+          def result(result_hint: nil)
             # Notice that we actually provide a detached cancellation here instead of defaulting to workflow
             # cancellation because we don't want workflow cancellation (or a user-provided cancellation to this result
             # call) to be able to interrupt waiting on a child that may be processing the cancellation.
@@ -29,7 +31,7 @@ def result
 
             case @resolution.status
             when :completed
-              @instance.payload_converter.from_payload(@resolution.completed.result)
+              @instance.payload_converter.from_payload(@resolution.completed.result, hint: result_hint || @result_hint)
             when :failed
               raise @instance.failure_converter.from_failure(@resolution.failed.failure, @instance.payload_converter)
             when :cancelled
@@ -44,8 +46,8 @@ def _resolve(resolution)
             @resolution = resolution
           end
 
-          def signal(signal, *args, cancellation: Workflow.cancellation)
-            @instance.context._signal_child_workflow(id:, signal:, args:, cancellation:)
+          def signal(signal, *args, cancellation: Workflow.cancellation, arg_hints: nil)
+            @instance.context._signal_child_workflow(id:, signal:, args:, cancellation:, arg_hints:)
           end
         end
       end
diff --git a/temporalio/lib/temporalio/internal/worker/workflow_instance/context.rb b/temporalio/lib/temporalio/internal/worker/workflow_instance/context.rb
index 84380d52..eaddb83f 100644
--- a/temporalio/lib/temporalio/internal/worker/workflow_instance/context.rb
+++ b/temporalio/lib/temporalio/internal/worker/workflow_instance/context.rb
@@ -86,16 +86,21 @@ def execute_activity(
             cancellation_type:,
             activity_id:,
             disable_eager_execution:,
-            priority:
+            priority:,
+            arg_hints:,
+            result_hint:
           )
-            activity = case activity
-                       when Class
-                         Activity::Definition::Info.from_activity(activity).name&.to_s
-                       when Symbol, String
-                         activity.to_s
-                       else
-                         raise ArgumentError, 'Activity must be a definition class, or a symbol/string'
-                       end
+            activity, defn_arg_hints, defn_result_hint =
+              case activity
+              when Class
+                defn = Activity::Definition::Info.from_activity(activity)
+                [defn.name&.to_s, defn.arg_hints, defn.result_hint]
+              when Symbol, String
+                [activity.to_s, nil, nil]
+              else
+                raise ArgumentError,
+                      'Activity must be a definition class, or a symbol/string'
+              end
             raise 'Cannot invoke dynamic activities' unless activity
 
             @outbound.execute_activity(
@@ -114,6 +119,8 @@ def execute_activity(
                 activity_id:,
                 disable_eager_execution: disable_eager_execution || @instance.disable_eager_activity_execution,
                 priority:,
+                arg_hints: arg_hints || defn_arg_hints,
+                result_hint: result_hint || defn_result_hint,
                 headers: {}
               )
             )
@@ -129,16 +136,20 @@ def execute_local_activity(
             local_retry_threshold:,
             cancellation:,
             cancellation_type:,
-            activity_id:
+            activity_id:,
+            arg_hints:,
+            result_hint:
           )
-            activity = case activity
-                       when Class
-                         Activity::Definition::Info.from_activity(activity).name&.to_s
-                       when Symbol, String
-                         activity.to_s
-                       else
-                         raise ArgumentError, 'Activity must be a definition class, or a symbol/string'
-                       end
+            activity, defn_arg_hints, defn_result_hint =
+              case activity
+              when Class
+                defn = Activity::Definition::Info.from_activity(activity)
+                [defn.name&.to_s, defn.arg_hints, defn.result_hint]
+              when Symbol, String
+                [activity.to_s, nil, nil]
+              else
+                raise ArgumentError, 'Activity must be a definition class, or a symbol/string'
+              end
             raise 'Cannot invoke dynamic activities' unless activity
 
             @outbound.execute_local_activity(
@@ -153,6 +164,8 @@ def execute_local_activity(
                 cancellation:,
                 cancellation_type:,
                 activity_id:,
+                arg_hints: arg_hints || defn_arg_hints,
+                result_hint: result_hint || defn_result_hint,
                 headers: {}
               )
             )
@@ -262,11 +275,15 @@ def start_child_workflow(
             cron_schedule:,
             memo:,
             search_attributes:,
-            priority:
+            priority:,
+            arg_hints:,
+            result_hint:
           )
+            workflow, defn_arg_hints, defn_result_hint =
+              Workflow::Definition._workflow_type_and_hints_from_workflow_parameter(workflow)
             @outbound.start_child_workflow(
               Temporalio::Worker::Interceptor::Workflow::StartChildWorkflowInput.new(
-                workflow: Workflow::Definition._workflow_type_from_workflow_parameter(workflow),
+                workflow:,
                 args:,
                 id:,
                 task_queue:,
@@ -284,6 +301,8 @@ def start_child_workflow(
                 memo:,
                 search_attributes:,
                 priority:,
+                arg_hints: arg_hints || defn_arg_hints,
+                result_hint: result_hint || defn_result_hint,
                 headers: {}
               )
             )
@@ -370,26 +389,30 @@ def _outbound=(outbound)
             @outbound = outbound
           end
 
-          def _signal_child_workflow(id:, signal:, args:, cancellation:)
+          def _signal_child_workflow(id:, signal:, args:, cancellation:, arg_hints:)
+            signal, defn_arg_hints = Workflow::Definition::Signal._name_and_hints_from_parameter(signal)
             @outbound.signal_child_workflow(
               Temporalio::Worker::Interceptor::Workflow::SignalChildWorkflowInput.new(
                 id:,
-                signal: Workflow::Definition::Signal._name_from_parameter(signal),
+                signal:,
                 args:,
                 cancellation:,
+                arg_hints: arg_hints || defn_arg_hints,
                 headers: {}
               )
             )
           end
 
-          def _signal_external_workflow(id:, run_id:, signal:, args:, cancellation:)
+          def _signal_external_workflow(id:, run_id:, signal:, args:, cancellation:, arg_hints:)
+            signal, defn_arg_hints = Workflow::Definition::Signal._name_and_hints_from_parameter(signal)
             @outbound.signal_external_workflow(
               Temporalio::Worker::Interceptor::Workflow::SignalExternalWorkflowInput.new(
                 id:,
                 run_id:,
-                signal: Workflow::Definition::Signal._name_from_parameter(signal),
+                signal:,
                 args:,
                 cancellation:,
+                arg_hints: arg_hints || defn_arg_hints,
                 headers: {}
               )
             )
diff --git a/temporalio/lib/temporalio/internal/worker/workflow_instance/external_workflow_handle.rb b/temporalio/lib/temporalio/internal/worker/workflow_instance/external_workflow_handle.rb
index c880f2c3..fb6cf494 100644
--- a/temporalio/lib/temporalio/internal/worker/workflow_instance/external_workflow_handle.rb
+++ b/temporalio/lib/temporalio/internal/worker/workflow_instance/external_workflow_handle.rb
@@ -18,8 +18,8 @@ def initialize(id:, run_id:, instance:) # rubocop:disable Lint/MissingSuper
             @instance = instance
           end
 
-          def signal(signal, *args, cancellation: Workflow.cancellation)
-            @instance.context._signal_external_workflow(id:, run_id:, signal:, args:, cancellation:)
+          def signal(signal, *args, cancellation: Workflow.cancellation, arg_hints: nil)
+            @instance.context._signal_external_workflow(id:, run_id:, signal:, args:, cancellation:, arg_hints:)
           end
 
           def cancel
diff --git a/temporalio/lib/temporalio/internal/worker/workflow_instance/outbound_implementation.rb b/temporalio/lib/temporalio/internal/worker/workflow_instance/outbound_implementation.rb
index 99ad747d..a1bf206e 100644
--- a/temporalio/lib/temporalio/internal/worker/workflow_instance/outbound_implementation.rb
+++ b/temporalio/lib/temporalio/internal/worker/workflow_instance/outbound_implementation.rb
@@ -56,7 +56,8 @@ def execute_activity(input)
               raise ArgumentError, 'Activity must have schedule_to_close_timeout or start_to_close_timeout'
             end
 
-            execute_activity_with_local_backoffs(local: false, cancellation: input.cancellation) do
+            execute_activity_with_local_backoffs(local: false, cancellation: input.cancellation,
+                                                 result_hint: input.result_hint) do
               seq = (@activity_counter += 1)
               @instance.add_command(
                 Bridge::Api::WorkflowCommands::WorkflowCommand.new(
@@ -66,7 +67,9 @@ def execute_activity(input)
                     activity_type: input.activity,
                     task_queue: input.task_queue,
                     headers: ProtoUtils.headers_to_proto_hash(input.headers, @instance.payload_converter),
-                    arguments: ProtoUtils.convert_to_payload_array(@instance.payload_converter, input.args),
+                    arguments: ProtoUtils.convert_to_payload_array(
+                      @instance.payload_converter, input.args, hints: input.arg_hints
+                    ),
                     schedule_to_close_timeout: ProtoUtils.seconds_to_duration(input.schedule_to_close_timeout),
                     schedule_to_start_timeout: ProtoUtils.seconds_to_duration(input.schedule_to_start_timeout),
                     start_to_close_timeout: ProtoUtils.seconds_to_duration(input.start_to_close_timeout),
@@ -90,7 +93,8 @@ def execute_local_activity(input)
 
             @instance.assert_valid_local_activity.call(input.activity)
 
-            execute_activity_with_local_backoffs(local: true, cancellation: input.cancellation) do |do_backoff|
+            execute_activity_with_local_backoffs(local: true, cancellation: input.cancellation,
+                                                 result_hint: input.result_hint) do |do_backoff|
               seq = (@activity_counter += 1)
               @instance.add_command(
                 Bridge::Api::WorkflowCommands::WorkflowCommand.new(
@@ -99,7 +103,9 @@ def execute_local_activity(input)
                     activity_id: input.activity_id || seq.to_s,
                     activity_type: input.activity,
                     headers: ProtoUtils.headers_to_proto_hash(input.headers, @instance.payload_converter),
-                    arguments: ProtoUtils.convert_to_payload_array(@instance.payload_converter, input.args),
+                    arguments: ProtoUtils.convert_to_payload_array(
+                      @instance.payload_converter, input.args, hints: input.arg_hints
+                    ),
                     schedule_to_close_timeout: ProtoUtils.seconds_to_duration(input.schedule_to_close_timeout),
                     schedule_to_start_timeout: ProtoUtils.seconds_to_duration(input.schedule_to_start_timeout),
                     start_to_close_timeout: ProtoUtils.seconds_to_duration(input.start_to_close_timeout),
@@ -115,7 +121,7 @@ def execute_local_activity(input)
             end
           end
 
-          def execute_activity_with_local_backoffs(local:, cancellation:, &)
+          def execute_activity_with_local_backoffs(local:, cancellation:, result_hint:, &)
             # We do not even want to schedule if the cancellation is already cancelled. We choose to use canceled
             # failure instead of wrapping in activity failure which is similar to what other SDKs do, with the accepted
             # tradeoff that it makes rescue more difficult (hence the presence of Error.canceled? helper).
@@ -124,7 +130,7 @@ def execute_activity_with_local_backoffs(local:, cancellation:, &)
             # This has to be done in a loop for local activity backoff
             last_local_backoff = nil
             loop do
-              result = execute_activity_once(local:, cancellation:, last_local_backoff:, &)
+              result = execute_activity_once(local:, cancellation:, last_local_backoff:, result_hint:, &)
               return result unless result.is_a?(Bridge::Api::ActivityResult::DoBackoff)
 
               # @type var result: untyped
@@ -136,7 +142,7 @@ def execute_activity_with_local_backoffs(local:, cancellation:, &)
           end
 
           # If this doesn't raise, it returns success | DoBackoff
-          def execute_activity_once(local:, cancellation:, last_local_backoff:, &)
+          def execute_activity_once(local:, cancellation:, last_local_backoff:, result_hint:, &)
             # Add to pending activities (removed by the resolver)
             seq = yield last_local_backoff
             @instance.pending_activities[seq] = Fiber.current
@@ -169,7 +175,7 @@ def execute_activity_once(local:, cancellation:, last_local_backoff:, &)
 
             case resolution.status
             when :completed
-              @instance.payload_converter.from_payload(resolution.completed.result)
+              @instance.payload_converter.from_payload(resolution.completed.result, hint: result_hint)
             when :failed
               raise @instance.failure_converter.from_failure(resolution.failed.failure, @instance.payload_converter)
             when :cancelled
@@ -193,6 +199,7 @@ def signal_child_workflow(input)
               signal: input.signal,
               args: input.args,
               cancellation: input.cancellation,
+              arg_hints: input.arg_hints,
               headers: input.headers
             )
           end
@@ -205,11 +212,12 @@ def signal_external_workflow(input)
               signal: input.signal,
               args: input.args,
               cancellation: input.cancellation,
+              arg_hints: input.arg_hints,
               headers: input.headers
             )
           end
 
-          def _signal_external_workflow(id:, run_id:, child:, signal:, args:, cancellation:, headers:)
+          def _signal_external_workflow(id:, run_id:, child:, signal:, args:, cancellation:, arg_hints:, headers:)
             raise Error::CanceledError, 'Signal canceled before scheduled' if cancellation.canceled?
 
             # Add command
@@ -217,7 +225,7 @@ def _signal_external_workflow(id:, run_id:, child:, signal:, args:, cancellation
             cmd = Bridge::Api::WorkflowCommands::SignalExternalWorkflowExecution.new(
               seq:,
               signal_name: signal,
-              args: ProtoUtils.convert_to_payload_array(@instance.payload_converter, args),
+              args: ProtoUtils.convert_to_payload_array(@instance.payload_converter, args, hints: arg_hints),
               headers: ProtoUtils.headers_to_proto_hash(headers, @instance.payload_converter)
             )
             if child
@@ -327,7 +335,8 @@ def start_child_workflow(input)
                   workflow_id: input.id,
                   workflow_type: input.workflow,
                   task_queue: input.task_queue,
-                  input: ProtoUtils.convert_to_payload_array(@instance.payload_converter, input.args),
+                  input: ProtoUtils.convert_to_payload_array(@instance.payload_converter, input.args,
+                                                             hints: input.arg_hints),
                   workflow_execution_timeout: ProtoUtils.seconds_to_duration(input.execution_timeout),
                   workflow_run_timeout: ProtoUtils.seconds_to_duration(input.run_timeout),
                   workflow_task_timeout: ProtoUtils.seconds_to_duration(input.task_timeout),
@@ -374,7 +383,8 @@ def start_child_workflow(input)
                 first_execution_run_id: resolution.succeeded.run_id,
                 instance: @instance,
                 cancellation: input.cancellation,
-                cancel_callback_key:
+                cancel_callback_key:,
+                result_hint: input.result_hint
               )
               @instance.pending_child_workflows[seq] = handle
               handle
diff --git a/temporalio/lib/temporalio/testing/workflow_environment.rb b/temporalio/lib/temporalio/testing/workflow_environment.rb
index 569370e1..d5e4d23c 100644
--- a/temporalio/lib/temporalio/testing/workflow_environment.rb
+++ b/temporalio/lib/temporalio/testing/workflow_environment.rb
@@ -394,8 +394,8 @@ def initialize(handle, env)
           end
 
           # @!visibility private
-          def result(follow_runs: true, rpc_options: nil)
-            @env.time_skipping_unlocked { super(follow_runs:, rpc_options:) }
+          def result(follow_runs: true, result_hint: nil, rpc_options: nil)
+            @env.time_skipping_unlocked { super(follow_runs:, result_hint:, rpc_options:) }
           end
         end
       end
diff --git a/temporalio/lib/temporalio/worker/interceptor.rb b/temporalio/lib/temporalio/worker/interceptor.rb
index 30fb8afb..fffc12ea 100644
--- a/temporalio/lib/temporalio/worker/interceptor.rb
+++ b/temporalio/lib/temporalio/worker/interceptor.rb
@@ -22,6 +22,7 @@ def intercept_activity(next_interceptor)
         ExecuteInput = Data.define(
           :proc,
           :args,
+          :result_hint,
           :headers
         )
 
@@ -59,7 +60,8 @@ def execute(input)
 
         # Input for {Outbound.heartbeat}.
         HeartbeatInput = Data.define(
-          :details
+          :details,
+          :detail_hints
         )
 
         # Outbound interceptor for intercepting outbound activity calls. This should be extended by users needing to
@@ -216,8 +218,10 @@ def handle_update(input)
           :cancellation_type,
           :activity_id,
           :disable_eager_execution,
-          :headers,
-          :priority
+          :priority,
+          :arg_hints,
+          :result_hint,
+          :headers
         )
 
         # Input for {Outbound.execute_local_activity}.
@@ -232,6 +236,8 @@ def handle_update(input)
           :cancellation,
           :cancellation_type,
           :activity_id,
+          :arg_hints,
+          :result_hint,
           :headers
         )
 
@@ -246,6 +252,7 @@ def handle_update(input)
           :signal,
           :args,
           :cancellation,
+          :arg_hints,
           :headers
         )
 
@@ -256,6 +263,7 @@ def handle_update(input)
           :signal,
           :args,
           :cancellation,
+          :arg_hints,
           :headers
         )
 
@@ -285,8 +293,10 @@ def handle_update(input)
           :cron_schedule,
           :memo,
           :search_attributes,
-          :headers,
-          :priority
+          :priority,
+          :arg_hints,
+          :result_hint,
+          :headers
         )
 
         # Outbound interceptor for intercepting outbound workflow calls. This should be extended by users needing to
diff --git a/temporalio/lib/temporalio/workflow.rb b/temporalio/lib/temporalio/workflow.rb
index bbe41668..28c4a573 100644
--- a/temporalio/lib/temporalio/workflow.rb
+++ b/temporalio/lib/temporalio/workflow.rb
@@ -132,6 +132,10 @@ def self.deprecate_patch(patch_id)
     #   run there. If `false` (the default), eager execution may still be disabled at the worker level or may not be
     #   requested due to lack of available slots.
     # @param priority [Priority] Priority of the activity. This is currently experimental.
+    # @param arg_hints [Array<Object>, nil] Overrides converter hints for arguments if any. If unset/nil and the
+    #   activity definition has arg hints, those are used by default.
+    # @param result_hint [Object, nil] Overrides converter hint for result if any. If unset/nil and the activity
+    #   definition has result hint, it is used by default.
     #
     # @return [Object] Result of the activity.
     # @raise [Error::ActivityError] Activity failed (and retry was disabled or exhausted).
@@ -151,13 +155,15 @@ def self.execute_activity(
       cancellation_type: ActivityCancellationType::TRY_CANCEL,
       activity_id: nil,
       disable_eager_execution: false,
-      priority: Priority.default
+      priority: Priority.default,
+      arg_hints: nil,
+      result_hint: nil
     )
       _current.execute_activity(
         activity, *args,
         task_queue:, summary:, schedule_to_close_timeout:, schedule_to_start_timeout:, start_to_close_timeout:,
         heartbeat_timeout:, retry_policy:, cancellation:, cancellation_type:, activity_id:, disable_eager_execution:,
-        priority:
+        priority:, arg_hints:, result_hint:
       )
     end
 
@@ -180,13 +186,15 @@ def self.execute_child_workflow(
       cron_schedule: nil,
       memo: nil,
       search_attributes: nil,
-      priority: Priority.default
+      priority: Priority.default,
+      arg_hints: nil,
+      result_hint: nil
     )
       start_child_workflow(
         workflow, *args,
         id:, task_queue:, static_summary:, static_details:, cancellation:, cancellation_type:,
         parent_close_policy:, execution_timeout:, run_timeout:, task_timeout:, id_reuse_policy:,
-        retry_policy:, cron_schedule:, memo:, search_attributes:, priority:
+        retry_policy:, cron_schedule:, memo:, search_attributes:, priority:, arg_hints:, result_hint:
       ).result
     end
 
@@ -217,6 +225,10 @@ def self.execute_child_workflow(
     #   workflow.
     # @param activity_id [String, nil] Optional unique identifier for the activity. This is an advanced setting that
     #   should not be set unless users are sure they need to. Contact Temporal before setting this value.
+    # @param arg_hints [Array<Object>, nil] Overrides converter hints for arguments if any. If unset/nil and the
+    #   activity definition has arg hints, those are used by default.
+    # @param result_hint [Object, nil] Overrides converter hint for result if any. If unset/nil and the activity
+    #   definition has result hint, it is used by default.
     #
     # @return [Object] Result of the activity.
     # @raise [Error::ActivityError] Activity failed (and retry was disabled or exhausted).
@@ -232,12 +244,15 @@ def self.execute_local_activity(
       local_retry_threshold: nil,
       cancellation: Workflow.cancellation,
       cancellation_type: ActivityCancellationType::TRY_CANCEL,
-      activity_id: nil
+      activity_id: nil,
+      arg_hints: nil,
+      result_hint: nil
     )
       _current.execute_local_activity(
         activity, *args,
         schedule_to_close_timeout:, schedule_to_start_timeout:, start_to_close_timeout:,
-        retry_policy:, local_retry_threshold:, cancellation:, cancellation_type:, activity_id:
+        retry_policy:, local_retry_threshold:, cancellation:, cancellation_type:,
+        activity_id:, arg_hints:, result_hint:
       )
     end
 
@@ -378,6 +393,10 @@ def self.sleep(duration, summary: nil, cancellation: Workflow.cancellation)
     # @param memo [Hash{String, Symbol => Object}, nil] Memo for the workflow.
     # @param search_attributes [SearchAttributes, nil] Search attributes for the workflow.
     # @param priority [Priority] Priority of the workflow. This is currently experimental.
+    # @param arg_hints [Array<Object>, nil] Overrides converter hints for arguments if any. If unset/nil and the
+    #   workflow definition has arg hints, those are used by default.
+    # @param result_hint [Object, nil] Overrides converter hint for result if any. If unset/nil and the workflow
+    #   definition has result hint, it is used by default.
     #
     # @return [ChildWorkflowHandle] Workflow handle to the started workflow.
     # @raise [Error::WorkflowAlreadyStartedError] Workflow already exists for the ID.
@@ -400,13 +419,15 @@ def self.start_child_workflow(
       cron_schedule: nil,
       memo: nil,
       search_attributes: nil,
-      priority: Priority.default
+      priority: Priority.default,
+      arg_hints: nil,
+      result_hint: nil
     )
       _current.start_child_workflow(
         workflow, *args,
         id:, task_queue:, static_summary:, static_details:, cancellation:, cancellation_type:,
         parent_close_policy:, execution_timeout:, run_timeout:, task_timeout:, id_reuse_policy:,
-        retry_policy:, cron_schedule:, memo:, search_attributes:, priority:
+        retry_policy:, cron_schedule:, memo:, search_attributes:, priority:, arg_hints:, result_hint:
       )
     end
 
@@ -542,7 +563,7 @@ def self.durable_scheduler_disabled(&)
     # Error that is raised by a workflow out of the primary workflow method to issue a continue-as-new.
     class ContinueAsNewError < Error
       attr_accessor :args, :workflow, :task_queue, :run_timeout, :task_timeout,
-                    :retry_policy, :memo, :search_attributes, :headers
+                    :retry_policy, :memo, :search_attributes, :arg_hints, :headers
 
       # Create a continue as new error.
       #
@@ -561,6 +582,8 @@ class ContinueAsNewError < Error
       #   is used.
       # @param search_attributes [SearchAttributes, nil] Search attributes for the workflow. If unset/nil, the current
       #   workflow search attributes are used.
+      # @param arg_hints [Array<Object>, nil] Overrides converter hints for arguments if any. If unset/nil and the
+      #   workflow definition has arg hints, those are used by default.
       # @param headers [Hash<String, Object>] Headers for the workflow. The default is _not_ carried over from the
       #   current workflow.
       def initialize(
@@ -572,6 +595,7 @@ def initialize(
         retry_policy: nil,
         memo: nil,
         search_attributes: nil,
+        arg_hints: nil,
         headers: {}
       )
         super('Continue as new')
@@ -583,6 +607,7 @@ def initialize(
         @retry_policy = retry_policy
         @memo = memo
         @search_attributes = search_attributes
+        @arg_hints = arg_hints
         @headers = headers
         Workflow._current.initialize_continue_as_new_error(self)
       end
diff --git a/temporalio/lib/temporalio/workflow/child_workflow_handle.rb b/temporalio/lib/temporalio/workflow/child_workflow_handle.rb
index 12cf8119..43086504 100644
--- a/temporalio/lib/temporalio/workflow/child_workflow_handle.rb
+++ b/temporalio/lib/temporalio/workflow/child_workflow_handle.rb
@@ -21,12 +21,18 @@ def first_execution_run_id
         raise NotImplementedError
       end
 
+      # @return [Object, nil] Hint for the result if any.
+      def result_hint
+        raise NotImplementedError
+      end
+
       # Wait for the result.
       #
+      # @param result_hint [Object, nil] Override the result hint, or if nil uses the one on the handle.
       # @return [Object] Result of the child workflow.
       #
       # @raise [Error::ChildWorkflowError] Workflow failed with +cause+ as the cause.
-      def result
+      def result(result_hint: nil)
         raise NotImplementedError
       end
 
@@ -35,7 +41,9 @@ def result
       # @param signal [Workflow::Definition::Signal, Symbol, String] Signal definition or name.
       # @param args [Array<Object>] Signal args.
       # @param cancellation [Cancellation] Cancellation for canceling the signalling.
-      def signal(signal, *args, cancellation: Workflow.cancellation)
+      # @param arg_hints [Array<Object>, nil] Overrides converter hints for arguments if any. If unset/nil and the
+      #   signal definition has arg hints, those are used by default.
+      def signal(signal, *args, cancellation: Workflow.cancellation, arg_hints: nil)
         raise NotImplementedError
       end
     end
diff --git a/temporalio/lib/temporalio/workflow/definition.rb b/temporalio/lib/temporalio/workflow/definition.rb
index 2f21f5e3..33d0dfe0 100644
--- a/temporalio/lib/temporalio/workflow/definition.rb
+++ b/temporalio/lib/temporalio/workflow/definition.rb
@@ -47,6 +47,21 @@ def workflow_raw_args(value = true) # rubocop:disable Style/OptionalBooleanParam
           @workflow_raw_args = value
         end
 
+        # Add workflow hints to be passed to converter for workflow args.
+        #
+        # @param hints [Array<Object>] Hints to add.
+        def workflow_arg_hint(*hints)
+          @workflow_arg_hints ||= []
+          @workflow_arg_hints.concat(hints)
+        end
+
+        # Set workflow result hint to be passed to converter for workflow result.
+        #
+        # @param hint [Object] Hint to set.
+        def workflow_result_hint(hint)
+          @workflow_result_hint = hint
+        end
+
         # Configure workflow failure exception types. This sets the types of exceptions that, if a
         # workflow-thrown exception extends, will cause the workflow/update to fail instead of suspending the workflow
         # via task failure. These are applied in addition to the worker option. If {::Exception} is set, it effectively
@@ -121,16 +136,20 @@ def workflow_init(value = true) # rubocop:disable Style/OptionalBooleanParameter
         #   {Converters::RawValue} which is a raw payload wrapper, convertible with {Workflow.payload_converter}.
         # @param unfinished_policy [HandlerUnfinishedPolicy] How to treat unfinished handlers if they are still running
         #   when the workflow ends. The default warns, but this can be disabled.
+        # @param arg_hints [Array<Object>, nil] Argument hint(s) for the signal.
         def workflow_signal(
           name: nil,
           description: nil,
           dynamic: false,
           raw_args: false,
-          unfinished_policy: HandlerUnfinishedPolicy::WARN_AND_ABANDON
+          unfinished_policy: HandlerUnfinishedPolicy::WARN_AND_ABANDON,
+          arg_hints: nil
         )
           raise 'Cannot provide name if dynamic is true' if name && dynamic
 
-          self.pending_handler_details = { type: :signal, name:, description:, dynamic:, raw_args:, unfinished_policy: }
+          self.pending_handler_details =
+            { type: :signal, name:, description:, dynamic:, raw_args:, unfinished_policy:,
+              arg_hints: Array(arg_hints) }
         end
 
         # Mark the next method as a workflow query with a default name as the name of the method. Queries can not have
@@ -144,15 +163,20 @@ def workflow_signal(
         #   it is useful to have the second parameter be `*args` and `raw_args` be true.
         # @param raw_args [Boolean] If true, does not convert arguments, but instead provides each argument as
         #   {Converters::RawValue} which is a raw payload wrapper, convertible with {Workflow.payload_converter}.
+        # @param arg_hints [Object, Array<Object>, nil] Argument hint(s) for the query.
+        # @param result_hint [Object, nil] Result hint for the query.
         def workflow_query(
           name: nil,
           description: nil,
           dynamic: false,
-          raw_args: false
+          raw_args: false,
+          arg_hints: nil,
+          result_hint: nil
         )
           raise 'Cannot provide name if dynamic is true' if name && dynamic
 
-          self.pending_handler_details = { type: :query, name:, description:, dynamic:, raw_args: }
+          self.pending_handler_details = { type: :query, name:, description:, dynamic:, raw_args:,
+                                           arg_hints: Array(arg_hints), result_hint: }
         end
 
         # Mark the next method as a workflow update with a default name as the name of the method. Updates can return
@@ -168,16 +192,21 @@ def workflow_query(
         #   {Converters::RawValue} which is a raw payload wrapper, convertible with {Workflow.payload_converter}.
         # @param unfinished_policy [HandlerUnfinishedPolicy] How to treat unfinished handlers if they are still running
         #   when the workflow ends. The default warns, but this can be disabled.
+        # @param arg_hints [Object, Array<Object>, nil] Argument hint(s) for the update.
+        # @param result_hint [Object, nil] Result hint for the update.
         def workflow_update(
           name: nil,
           description: nil,
           dynamic: false,
           raw_args: false,
-          unfinished_policy: HandlerUnfinishedPolicy::WARN_AND_ABANDON
+          unfinished_policy: HandlerUnfinishedPolicy::WARN_AND_ABANDON,
+          arg_hints: nil,
+          result_hint: nil
         )
           raise 'Cannot provide name if dynamic is true' if name && dynamic
 
-          self.pending_handler_details = { type: :update, name:, description:, dynamic:, raw_args:, unfinished_policy: }
+          self.pending_handler_details = { type: :update, name:, description:, dynamic:, raw_args:, unfinished_policy:,
+                                           arg_hints: Array(arg_hints), result_hint: }
         end
 
         # Mark the next method as a workflow update validator to the given update method. The validator is expected to
@@ -275,14 +304,17 @@ def self.method_added(method_name)
               to_invoke: method_name,
               description: handler[:description],
               raw_args: handler[:raw_args],
-              unfinished_policy: handler[:unfinished_policy]
+              unfinished_policy: handler[:unfinished_policy],
+              arg_hints: handler[:arg_hints]
             ), @workflow_signals, [@workflow_queries, @workflow_updates]]
           when :query
             [Query.new(
               name: handler[:dynamic] ? nil : (handler[:name] || method_name).to_s,
               to_invoke: method_name,
               description: handler[:description],
-              raw_args: handler[:raw_args]
+              raw_args: handler[:raw_args],
+              arg_hints: handler[:arg_hints],
+              result_hint: handler[:result_hint]
             ), @workflow_queries, [@workflow_signals, @workflow_updates]]
           when :update
             [Update.new(
@@ -290,7 +322,9 @@ def self.method_added(method_name)
               to_invoke: method_name,
               description: handler[:description],
               raw_args: handler[:raw_args],
-              unfinished_policy: handler[:unfinished_policy]
+              unfinished_policy: handler[:unfinished_policy],
+              arg_hints: handler[:arg_hints],
+              result_hint: handler[:result_hint]
             ), @workflow_updates, [@workflow_signals, @workflow_queries]]
           when :dynamic_options
             raise 'Dynamic options method already set' if @dynamic_options_method
@@ -334,7 +368,7 @@ def self._workflow_definition
       end
 
       # @!visibility private
-      def self._workflow_type_from_workflow_parameter(workflow)
+      def self._workflow_type_and_hints_from_workflow_parameter(workflow)
         case workflow
         when Class
           unless workflow < Definition
@@ -342,11 +376,15 @@ def self._workflow_type_from_workflow_parameter(workflow)
           end
 
           info = Info.from_class(workflow)
-          info.name || raise(ArgumentError, 'Cannot pass dynamic workflow to start')
+          raise(ArgumentError, 'Cannot pass dynamic workflow to start') unless info.name
+
+          [info.name.to_s, info.arg_hints, info.result_hint]
         when Info
-          workflow.name || raise(ArgumentError, 'Cannot pass dynamic workflow to start')
+          raise(ArgumentError, 'Cannot pass dynamic workflow to start') unless workflow.name
+
+          [workflow.name.to_s, nil, nil]
         when String, Symbol
-          workflow.to_s
+          [workflow.to_s, nil, nil]
         else
           raise ArgumentError, 'Workflow is not a workflow class or string/symbol'
         end
@@ -448,7 +486,9 @@ def self._build_workflow_definition
           queries:,
           updates:,
           versioning_behavior: @versioning_behavior || VersioningBehavior::UNSPECIFIED,
-          dynamic_options_method: @dynamic_options_method
+          dynamic_options_method: @dynamic_options_method,
+          arg_hints: @workflow_arg_hints,
+          result_hint: @workflow_result_hint
         )
       end
 
@@ -462,7 +502,7 @@ def execute(*args)
       class Info
         attr_reader :workflow_class, :override_name, :dynamic, :init, :raw_args,
                     :failure_exception_types, :signals, :queries, :updates, :versioning_behavior,
-                    :dynamic_options_method
+                    :dynamic_options_method, :arg_hints, :result_hint
 
         # Derive the workflow definition info from the class.
         #
@@ -489,7 +529,9 @@ def initialize(
           queries: {},
           updates: {},
           versioning_behavior: VersioningBehavior::UNSPECIFIED,
-          dynamic_options_method: nil
+          dynamic_options_method: nil,
+          arg_hints: nil,
+          result_hint: nil
         )
           @workflow_class = workflow_class
           @override_name = override_name
@@ -502,6 +544,8 @@ def initialize(
           @updates = updates.dup.freeze
           @versioning_behavior = versioning_behavior
           @dynamic_options_method = dynamic_options_method
+          @arg_hints = arg_hints
+          @result_hint = result_hint
           Internal::ProtoUtils.assert_non_reserved_name(name)
         end
 
@@ -514,15 +558,17 @@ def name
       # A signal definition. This is usually built as a result of a {Definition.workflow_signal} method, but can be
       # manually created to set at runtime on {Workflow.signal_handlers}.
       class Signal
-        attr_reader :name, :to_invoke, :description, :raw_args, :unfinished_policy
+        attr_reader :name, :to_invoke, :description, :raw_args, :unfinished_policy, :arg_hints
 
         # @!visibility private
-        def self._name_from_parameter(signal)
+        def self._name_and_hints_from_parameter(signal)
           case signal
           when Workflow::Definition::Signal
-            signal.name || raise(ArgumentError, 'Cannot call dynamic signal directly')
+            raise(ArgumentError, 'Cannot call dynamic signal directly') unless signal.name
+
+            [signal.name, signal.arg_hints]
           when String, Symbol
-            signal.to_s
+            [signal.to_s, nil]
           else
             raise ArgumentError, 'Signal is not a definition or string/symbol'
           end
@@ -538,18 +584,21 @@ def self._name_from_parameter(signal)
         # @param raw_args [Boolean] Whether the parameters should be raw values.
         # @param unfinished_policy [HandlerUnfinishedPolicy] How the workflow reacts when this handler is still running
         #   on workflow completion.
+        # @param arg_hints [Array<Object>, nil] Argument hints for the signal.
         def initialize(
           name:,
           to_invoke:,
           description: nil,
           raw_args: false,
-          unfinished_policy: HandlerUnfinishedPolicy::WARN_AND_ABANDON
+          unfinished_policy: HandlerUnfinishedPolicy::WARN_AND_ABANDON,
+          arg_hints: nil
         )
           @name = name
           @to_invoke = to_invoke
           @description = description
           @raw_args = raw_args
           @unfinished_policy = unfinished_policy
+          @arg_hints = arg_hints
           Internal::ProtoUtils.assert_non_reserved_name(name)
         end
       end
@@ -557,15 +606,17 @@ def initialize(
       # A query definition. This is usually built as a result of a {Definition.workflow_query} method, but can be
       # manually created to set at runtime on {Workflow.query_handlers}.
       class Query
-        attr_reader :name, :to_invoke, :description, :raw_args
+        attr_reader :name, :to_invoke, :description, :raw_args, :arg_hints, :result_hint
 
         # @!visibility private
-        def self._name_from_parameter(query)
+        def self._name_and_hints_from_parameter(query)
           case query
           when Workflow::Definition::Query
-            query.name || raise(ArgumentError, 'Cannot call dynamic query directly')
+            raise(ArgumentError, 'Cannot call dynamic query directly') unless query.name
+
+            [query.name, query.arg_hints, query.result_hint]
           when String, Symbol
-            query.to_s
+            [query.to_s, nil, nil]
           else
             raise ArgumentError, 'Query is not a definition or string/symbol'
           end
@@ -579,16 +630,22 @@ def self._name_from_parameter(query)
         # @param description [String, nil] Description for this handler that may appear in CLI/UI. This is currently
         #   experimental.
         # @param raw_args [Boolean] Whether the parameters should be raw values.
+        # @param arg_hints [Array<Object>, nil] Argument hints for the query.
+        # @param result_hint [Object, nil] Result hints for the query.
         def initialize(
           name:,
           to_invoke:,
           description: nil,
-          raw_args: false
+          raw_args: false,
+          arg_hints: nil,
+          result_hint: nil
         )
           @name = name
           @to_invoke = to_invoke
           @description = description
           @raw_args = raw_args
+          @arg_hints = arg_hints
+          @result_hint = result_hint
           Internal::ProtoUtils.assert_non_reserved_name(name)
         end
       end
@@ -596,15 +653,18 @@ def initialize(
       # An update definition. This is usually built as a result of a {Definition.workflow_update} method, but can be
       # manually created to set at runtime on {Workflow.update_handlers}.
       class Update
-        attr_reader :name, :to_invoke, :description, :raw_args, :unfinished_policy, :validator_to_invoke
+        attr_reader :name, :to_invoke, :description, :raw_args, :unfinished_policy, :validator_to_invoke,
+                    :arg_hints, :result_hint
 
         # @!visibility private
-        def self._name_from_parameter(update)
+        def self._name_and_hints_from_parameter(update)
           case update
           when Workflow::Definition::Update
-            update.name || raise(ArgumentError, 'Cannot call dynamic update directly')
+            raise(ArgumentError, 'Cannot call dynamic update directly') unless update.name
+
+            [update.name, update.arg_hints, update.result_hint]
           when String, Symbol
-            update.to_s
+            [update.to_s, nil, nil]
           else
             raise ArgumentError, 'Update is not a definition or string/symbol'
           end
@@ -621,13 +681,17 @@ def self._name_from_parameter(update)
         # @param unfinished_policy [HandlerUnfinishedPolicy] How the workflow reacts when this handler is still running
         #   on workflow completion.
         # @param validator_to_invoke [Symbol, Proc, nil] Method name or proc validator to invoke.
+        # @param arg_hints [Array<Object>, nil] Argument hints for the update.
+        # @param result_hint [Object, nil] Result hints for the update.
         def initialize(
           name:,
           to_invoke:,
           description: nil,
           raw_args: false,
           unfinished_policy: HandlerUnfinishedPolicy::WARN_AND_ABANDON,
-          validator_to_invoke: nil
+          validator_to_invoke: nil,
+          arg_hints: nil,
+          result_hint: nil
         )
           @name = name
           @to_invoke = to_invoke
@@ -635,6 +699,8 @@ def initialize(
           @raw_args = raw_args
           @unfinished_policy = unfinished_policy
           @validator_to_invoke = validator_to_invoke
+          @arg_hints = arg_hints
+          @result_hint = result_hint
           Internal::ProtoUtils.assert_non_reserved_name(name)
         end
 
@@ -646,7 +712,9 @@ def _with_validator_to_invoke(validator_to_invoke)
             description:,
             raw_args:,
             unfinished_policy:,
-            validator_to_invoke:
+            validator_to_invoke:,
+            arg_hints:,
+            result_hint:
           )
         end
       end
diff --git a/temporalio/lib/temporalio/workflow/external_workflow_handle.rb b/temporalio/lib/temporalio/workflow/external_workflow_handle.rb
index 37e22100..0e2a0ef7 100644
--- a/temporalio/lib/temporalio/workflow/external_workflow_handle.rb
+++ b/temporalio/lib/temporalio/workflow/external_workflow_handle.rb
@@ -28,7 +28,9 @@ def run_id
       # @param signal [Workflow::Definition::Signal, Symbol, String] Signal definition or name.
       # @param args [Array<Object>] Signal args.
       # @param cancellation [Cancellation] Cancellation for canceling the signalling.
-      def signal(signal, *args, cancellation: Workflow.cancellation)
+      # @param arg_hints [Array<Object>, nil] Overrides converter hints for arguments if any. If unset/nil and the
+      #   signal definition has arg hints, those are used by default.
+      def signal(signal, *args, cancellation: Workflow.cancellation, arg_hints: nil)
         raise NotImplementedError
       end
 
diff --git a/temporalio/sig/temporalio/activity/context.rbs b/temporalio/sig/temporalio/activity/context.rbs
index dc671331..a3f3070c 100644
--- a/temporalio/sig/temporalio/activity/context.rbs
+++ b/temporalio/sig/temporalio/activity/context.rbs
@@ -10,7 +10,7 @@ module Temporalio
 
       def info: -> Info
       def instance: -> Definition?
-      def heartbeat: (*Object? details) -> void
+      def heartbeat: (*Object? details, ?detail_hints: Array[Object]?) -> void
       def cancellation: -> Cancellation
       def cancellation_details: -> CancellationDetails?
       def worker_shutdown_cancellation: -> Cancellation
diff --git a/temporalio/sig/temporalio/activity/definition.rbs b/temporalio/sig/temporalio/activity/definition.rbs
index 9b46d29e..70e3c978 100644
--- a/temporalio/sig/temporalio/activity/definition.rbs
+++ b/temporalio/sig/temporalio/activity/definition.rbs
@@ -6,12 +6,16 @@ module Temporalio
       def self.activity_cancel_raise: (bool cancel_raise) -> void
       def self.activity_dynamic: (?bool value) -> void
       def self.activity_raw_args: (?bool value) -> void
+      def self.activity_arg_hint: (*Object hints) -> void
+      def self.activity_result_hint: (Object? hint) -> void
   
       def self._activity_definition_details: -> {
         activity_name: String | Symbol | nil,
         activity_executor: Symbol,
         activity_cancel_raise: bool,
-        activity_raw_args: bool
+        activity_raw_args: bool,
+        activity_arg_hints: Array[Object]?,
+        activity_result_hint: Object?
       }
   
       def execute: (*untyped) -> untyped
@@ -23,6 +27,8 @@ module Temporalio
         attr_reader executor: Symbol
         attr_reader cancel_raise: bool
         attr_reader raw_args: bool
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
 
         def self.from_activity: (Definition | singleton(Definition) | Info activity) -> Info
 
@@ -31,7 +37,9 @@ module Temporalio
           ?instance: Object | Proc | nil,
           ?executor: Symbol,
           ?cancel_raise: bool,
-          ?raw_args: bool
+          ?raw_args: bool,
+          ?arg_hints: Array[Object]?,
+          ?result_hint: Object?
         ) { (?) -> untyped } -> void
       end
     end
diff --git a/temporalio/sig/temporalio/client.rbs b/temporalio/sig/temporalio/client.rbs
index 2ac202ab..84a63d42 100644
--- a/temporalio/sig/temporalio/client.rbs
+++ b/temporalio/sig/temporalio/client.rbs
@@ -85,8 +85,10 @@ module Temporalio
       ?search_attributes: SearchAttributes?,
       ?start_delay: duration?,
       ?request_eager_start: bool,
-      ?priority: Priority,
       ?versioning_override: VersioningOverride?,
+      ?priority: Priority,
+      ?arg_hints: Array[Object]?,
+      ?result_hint: Object?,
       ?rpc_options: RPCOptions?
     ) -> WorkflowHandle
 
@@ -108,16 +110,18 @@ module Temporalio
       ?search_attributes: SearchAttributes?,
       ?start_delay: duration?,
       ?request_eager_start: bool,
-      ?priority: Priority,
       ?versioning_override: VersioningOverride?,
-      ?follow_runs: bool,
+      ?priority: Priority,
+      ?arg_hints: Array[Object]?,
+      ?result_hint: Object?,
       ?rpc_options: RPCOptions?
     ) -> Object?
 
     def workflow_handle: (
       String workflow_id,
       ?run_id: String?,
-      ?first_execution_run_id: String?
+      ?first_execution_run_id: String?,
+      ?result_hint: Object?
     ) -> WorkflowHandle
 
     def start_update_with_start_workflow: (
@@ -126,6 +130,8 @@ module Temporalio
       start_workflow_operation: WithStartWorkflowOperation,
       wait_for_stage: WorkflowUpdateWaitStage::enum,
       ?id: String,
+      ?arg_hints: Array[Object]?,
+      ?result_hint: Object?,
       ?rpc_options: RPCOptions?
     ) -> WorkflowUpdateHandle
 
@@ -134,6 +140,8 @@ module Temporalio
       *Object? args,
       start_workflow_operation: WithStartWorkflowOperation,
       ?id: String,
+      ?arg_hints: Array[Object]?,
+      ?result_hint: Object?,
       ?rpc_options: RPCOptions?
     ) -> Object?
 
@@ -141,6 +149,7 @@ module Temporalio
       Workflow::Definition::Signal | Symbol | String signal,
       *Object? args,
       start_workflow_operation: WithStartWorkflowOperation,
+      ?arg_hints: Array[Object]?,
       ?rpc_options: RPCOptions?
     ) -> WorkflowHandle
 
diff --git a/temporalio/sig/temporalio/client/async_activity_handle.rbs b/temporalio/sig/temporalio/client/async_activity_handle.rbs
index 5d993bde..3f65aba6 100644
--- a/temporalio/sig/temporalio/client/async_activity_handle.rbs
+++ b/temporalio/sig/temporalio/client/async_activity_handle.rbs
@@ -12,22 +12,26 @@ module Temporalio
 
       def heartbeat: (
         *Object? details,
+        ?detail_hints: Array[Object]?,
         ?rpc_options: RPCOptions?
       ) -> void
 
       def complete: (
         ?Object? result,
+        ?result_hint: Object?,
         ?rpc_options: RPCOptions?
       ) -> void
 
       def fail: (
         Exception error,
         ?last_heartbeat_details: Array[Object?],
+        ?last_heartbeat_detail_hints: Array[Object]?,
         ?rpc_options: RPCOptions?
       ) -> void
 
       def report_cancellation: (
         *Object? details,
+        ?detail_hints: Array[Object]?,
         ?rpc_options: RPCOptions?
       ) -> void
 
diff --git a/temporalio/sig/temporalio/client/interceptor.rbs b/temporalio/sig/temporalio/client/interceptor.rbs
index 3e1e227e..2d0aee02 100644
--- a/temporalio/sig/temporalio/client/interceptor.rbs
+++ b/temporalio/sig/temporalio/client/interceptor.rbs
@@ -21,9 +21,11 @@ module Temporalio
         attr_reader search_attributes: SearchAttributes?
         attr_reader start_delay: duration?
         attr_reader request_eager_start: bool
-        attr_reader headers: Hash[String, Object?]
-        attr_reader priority: Priority
         attr_reader versioning_override: VersioningOverride?
+        attr_reader priority: Priority
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
+        attr_reader headers: Hash[String, Object?]
         attr_reader rpc_options: RPCOptions?
 
         def initialize: (
@@ -44,9 +46,11 @@ module Temporalio
           search_attributes: SearchAttributes?,
           start_delay: duration?,
           request_eager_start: bool,
-          headers: Hash[String, Object?],
-          priority: Priority,
           versioning_override: VersioningOverride?,
+          priority: Priority,
+          arg_hints: Array[Object]?,
+          result_hint: Object?,
+          headers: Hash[String, Object?],
           rpc_options: RPCOptions?
         ) -> void
       end
@@ -57,6 +61,8 @@ module Temporalio
         attr_reader args: Array[Object?]
         attr_reader wait_for_stage: WorkflowUpdateWaitStage::enum
         attr_reader start_workflow_operation: WithStartWorkflowOperation
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
         attr_reader headers: Hash[String, Object?]
         attr_reader rpc_options: RPCOptions?
 
@@ -66,6 +72,8 @@ module Temporalio
           args: Array[Object?],
           wait_for_stage: WorkflowUpdateWaitStage::enum,
           start_workflow_operation: WithStartWorkflowOperation,
+          arg_hints: Array[Object]?,
+          result_hint: Object?,
           headers: Hash[String, Object?],
           rpc_options: RPCOptions?
         ) -> void
@@ -75,12 +83,14 @@ module Temporalio
         attr_reader signal: String
         attr_reader args: Array[Object?]
         attr_reader start_workflow_operation: WithStartWorkflowOperation
+        attr_reader arg_hints: Array[Object]?
         attr_reader rpc_options: RPCOptions?
 
         def initialize: (
           signal: String,
           args: Array[Object?],
           start_workflow_operation: WithStartWorkflowOperation,
+          arg_hints: Array[Object]?,
           rpc_options: RPCOptions?
         ) -> void
       end
@@ -144,6 +154,7 @@ module Temporalio
         attr_reader run_id: String?
         attr_reader signal: String
         attr_reader args: Array[Object?]
+        attr_reader arg_hints: Array[Object]?
         attr_reader headers: Hash[String, Object?]
         attr_reader rpc_options: RPCOptions?
 
@@ -152,6 +163,7 @@ module Temporalio
           run_id: String?,
           signal: String,
           args: Array[Object?],
+          arg_hints: Array[Object]?,
           headers: Hash[String, Object?],
           rpc_options: RPCOptions?
         ) -> void
@@ -163,6 +175,8 @@ module Temporalio
         attr_reader query: String
         attr_reader args: Array[Object?]
         attr_reader reject_condition: WorkflowQueryRejectCondition::enum?
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
         attr_reader headers: Hash[String, Object?]
         attr_reader rpc_options: RPCOptions?
 
@@ -172,6 +186,8 @@ module Temporalio
           query: String,
           args: Array[Object?],
           reject_condition: WorkflowQueryRejectCondition::enum?,
+          arg_hints: Array[Object]?,
+          result_hint: Object?,
           headers: Hash[String, Object?],
           rpc_options: RPCOptions?
         ) -> void
@@ -184,6 +200,8 @@ module Temporalio
         attr_reader update: String
         attr_reader args: Array[Object?]
         attr_reader wait_for_stage: WorkflowUpdateWaitStage::enum
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
         attr_reader headers: Hash[String, Object?]
         attr_reader rpc_options: RPCOptions?
 
@@ -194,6 +212,8 @@ module Temporalio
           update: String,
           args: Array[Object?],
           wait_for_stage: WorkflowUpdateWaitStage::enum,
+          arg_hints: Array[Object]?,
+          result_hint: Object?,
           headers: Hash[String, Object?],
           rpc_options: RPCOptions?
         ) -> void
@@ -358,11 +378,13 @@ module Temporalio
       class HeartbeatAsyncActivityInput
         attr_reader task_token_or_id_reference: String | ActivityIDReference
         attr_reader details: Array[Object?]
+        attr_reader detail_hints: Array[Object]?
         attr_reader rpc_options: RPCOptions?
 
         def initialize: (
           task_token_or_id_reference: String | ActivityIDReference,
           details: Array[Object?],
+          detail_hints: Array[Object]?,
           rpc_options: RPCOptions?
         ) -> void
       end
@@ -370,11 +392,13 @@ module Temporalio
       class CompleteAsyncActivityInput
         attr_reader task_token_or_id_reference: String | ActivityIDReference
         attr_reader result: Object?
+        attr_reader result_hint: Object?
         attr_reader rpc_options: RPCOptions?
 
         def initialize: (
           task_token_or_id_reference: String | ActivityIDReference,
           result: Object?,
+          result_hint: Object?,
           rpc_options: RPCOptions?
         ) -> void
       end
@@ -383,12 +407,14 @@ module Temporalio
         attr_reader task_token_or_id_reference: String | ActivityIDReference
         attr_reader error: Exception
         attr_reader last_heartbeat_details: Array[Object?]
+        attr_reader last_heartbeat_detail_hints: Array[Object]?
         attr_reader rpc_options: RPCOptions?
 
         def initialize: (
           task_token_or_id_reference: String | ActivityIDReference,
           error: Exception,
           last_heartbeat_details: Array[Object?],
+          last_heartbeat_detail_hints: Array[Object]?,
           rpc_options: RPCOptions?
         ) -> void
       end
@@ -396,12 +422,13 @@ module Temporalio
       class ReportCancellationAsyncActivityInput
         attr_reader task_token_or_id_reference: String | ActivityIDReference
         attr_reader details: Array[Object?]
+        attr_reader detail_hints: Array[Object]?
         attr_reader rpc_options: RPCOptions?
 
         def initialize: (
           task_token_or_id_reference: String | ActivityIDReference,
           details: Array[Object?],
-          rpc_options: RPCOptions?
+          detail_hints: Array[Object]?,          rpc_options: RPCOptions?
         ) -> void
       end
 
diff --git a/temporalio/sig/temporalio/client/schedule.rbs b/temporalio/sig/temporalio/client/schedule.rbs
index 44014961..24f92d02 100644
--- a/temporalio/sig/temporalio/client/schedule.rbs
+++ b/temporalio/sig/temporalio/client/schedule.rbs
@@ -74,6 +74,7 @@ module Temporalio
           attr_reader retry_policy: RetryPolicy?
           attr_reader memo: Hash[String, Object?]?
           attr_reader search_attributes: SearchAttributes?
+          attr_reader arg_hints: Array[Object]?
           attr_reader headers: Hash[String, Object?]?
 
           def self.new: (
@@ -89,6 +90,7 @@ module Temporalio
             ?retry_policy: RetryPolicy?,
             ?memo: Hash[String, Object?]?,
             ?search_attributes: SearchAttributes?,
+            ?arg_hints: Array[Object]?,
             ?headers: Hash[String, Object?]?
           ) -> StartWorkflow
 
diff --git a/temporalio/sig/temporalio/client/with_start_workflow_operation.rbs b/temporalio/sig/temporalio/client/with_start_workflow_operation.rbs
index 6f21e864..7d66d74a 100644
--- a/temporalio/sig/temporalio/client/with_start_workflow_operation.rbs
+++ b/temporalio/sig/temporalio/client/with_start_workflow_operation.rbs
@@ -18,6 +18,8 @@ module Temporalio
         attr_reader memo: Hash[String | Symbol, Object?]?
         attr_reader search_attributes: SearchAttributes?
         attr_reader start_delay: duration?
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
         attr_reader headers: Hash[String, Object?]
 
         def initialize: (
@@ -37,6 +39,8 @@ module Temporalio
           memo: Hash[String | Symbol, Object?]?,
           search_attributes: SearchAttributes?,
           start_delay: duration?,
+          arg_hints: Array[Object]?,
+          result_hint: Object?,
           headers: Hash[String, Object?]
         ) -> void
       end
@@ -60,6 +64,8 @@ module Temporalio
         ?memo: Hash[String | Symbol, Object?]?,
         ?search_attributes: SearchAttributes?,
         ?start_delay: duration?,
+        ?arg_hints: Array[Object]?,
+        ?result_hint: Object?,
         ?headers: Hash[String, Object?]
       ) -> void
 
diff --git a/temporalio/sig/temporalio/client/workflow_handle.rbs b/temporalio/sig/temporalio/client/workflow_handle.rbs
index a0ad22fb..e95ffaa5 100644
--- a/temporalio/sig/temporalio/client/workflow_handle.rbs
+++ b/temporalio/sig/temporalio/client/workflow_handle.rbs
@@ -5,17 +5,20 @@ module Temporalio
       attr_reader run_id: String?
       attr_reader result_run_id: String?
       attr_reader first_execution_run_id: String?
+      attr_reader result_hint: Object?
 
       def initialize: (
         client: Client,
         id: String,
         run_id: String?,
         result_run_id: String?,
-        first_execution_run_id: String?
+        first_execution_run_id: String?,
+        result_hint: Object?
       ) -> void
 
       def result: (
         ?follow_runs: bool,
+        ?result_hint: Object?,
         ?rpc_options: RPCOptions?
       ) -> Object?
 
@@ -39,6 +42,7 @@ module Temporalio
       def signal: (
         Workflow::Definition::Signal | Symbol | String signal,
         *Object? args,
+        ?arg_hints: Array[Object]?,
         ?rpc_options: RPCOptions?
       ) -> void
 
@@ -46,6 +50,8 @@ module Temporalio
         Workflow::Definition::Query | Symbol | String query,
         *Object? args,
         ?reject_condition: WorkflowQueryRejectCondition::enum?,
+        ?arg_hints: Array[Object]?,
+        ?result_hint: Object?,
         ?rpc_options: RPCOptions?
       ) -> Object?
 
@@ -54,6 +60,8 @@ module Temporalio
         *Object? args,
         wait_for_stage: WorkflowUpdateWaitStage::enum,
         ?id: String,
+        ?arg_hints: Array[Object]?,
+        ?result_hint: Object?,
         ?rpc_options: RPCOptions?
       ) -> WorkflowUpdateHandle
 
@@ -61,12 +69,15 @@ module Temporalio
         Workflow::Definition::Update | Symbol | String update,
         *Object? args,
         ?id: String,
+        ?arg_hints: Array[Object]?,
+        ?result_hint: Object?,
         ?rpc_options: RPCOptions?
       ) -> Object?
 
       def update_handle: (
         String id,
-        ?specific_run_id: String?
+        ?specific_run_id: String?,
+        ?result_hint: Object?
       ) -> WorkflowUpdateHandle
 
       def cancel: (
diff --git a/temporalio/sig/temporalio/client/workflow_update_handle.rbs b/temporalio/sig/temporalio/client/workflow_update_handle.rbs
index 5bf4c3f8..8c13985c 100644
--- a/temporalio/sig/temporalio/client/workflow_update_handle.rbs
+++ b/temporalio/sig/temporalio/client/workflow_update_handle.rbs
@@ -4,18 +4,21 @@ module Temporalio
       attr_reader id: String
       attr_reader workflow_id: String
       attr_reader workflow_run_id: String?
+      attr_reader result_hint: Object?
 
       def initialize: (
         client: Client,
         id: String,
         workflow_id: String,
         workflow_run_id: String?,
-        known_outcome: untyped?
+        known_outcome: untyped?,
+        result_hint: Object?
       ) -> void
 
       def result_obtained?: -> bool
 
       def result: (
+        ?result_hint: Object?,
         ?rpc_options: RPCOptions?
       ) -> Object?
     end
diff --git a/temporalio/sig/temporalio/converters/data_converter.rbs b/temporalio/sig/temporalio/converters/data_converter.rbs
index 9f1b89b3..7056142c 100644
--- a/temporalio/sig/temporalio/converters/data_converter.rbs
+++ b/temporalio/sig/temporalio/converters/data_converter.rbs
@@ -13,11 +13,11 @@ module Temporalio
         ?payload_codec: PayloadCodec?
       ) -> void
 
-      def to_payload: (Object? value) -> untyped
-      def to_payloads: (Array[Object?] values) -> untyped
+      def to_payload: (Object? value, ?hint: Object?) -> untyped
+      def to_payloads: (Array[Object?] values, ?hints: Array[Object]?) -> untyped
 
-      def from_payload: (untyped payload) -> Object?
-      def from_payloads: (untyped payloads) -> Array[Object?]
+      def from_payload: (untyped payload, ?hint: Object?) -> Object?
+      def from_payloads: (untyped payloads, ?hints: Array[Object]?) -> Array[Object?]
 
       def to_failure: (Exception error) -> untyped
       def from_failure: (untyped failure) -> Exception
diff --git a/temporalio/sig/temporalio/converters/payload_converter.rbs b/temporalio/sig/temporalio/converters/payload_converter.rbs
index f0f6d9a9..113de88d 100644
--- a/temporalio/sig/temporalio/converters/payload_converter.rbs
+++ b/temporalio/sig/temporalio/converters/payload_converter.rbs
@@ -8,11 +8,11 @@ module Temporalio
         ?json_generate_options: Hash[Symbol, untyped]
       ) -> PayloadConverter
 
-      def to_payload: (Object? value) -> untyped
-      def to_payloads: (Array[Object?] values) -> untyped
+      def to_payload: (Object? value, ?hint: Object?) -> untyped
+      def to_payloads: (Array[Object?] values, ?hints: Array[Object]?) -> untyped
 
-      def from_payload: (untyped payload) -> Object?
-      def from_payloads: (untyped payloads) -> Array[Object?]
+      def from_payload: (untyped payload, ?hint: Object?) -> Object?
+      def from_payloads: (untyped payloads, ?hints: Array[Object]?) -> Array[Object?]
     end
   end
 end
\ No newline at end of file
diff --git a/temporalio/sig/temporalio/converters/payload_converter/encoding.rbs b/temporalio/sig/temporalio/converters/payload_converter/encoding.rbs
index af7b8714..2bbee826 100644
--- a/temporalio/sig/temporalio/converters/payload_converter/encoding.rbs
+++ b/temporalio/sig/temporalio/converters/payload_converter/encoding.rbs
@@ -4,9 +4,9 @@ module Temporalio
       class Encoding
         def encoding: -> String
 
-        def to_payload: (Object? value) -> untyped?
+        def to_payload: (Object? value, ?hint: Object?) -> untyped?
 
-        def from_payload: (untyped payload) -> Object?
+        def from_payload: (untyped payload, ?hint: Object?) -> Object?
       end
     end
   end
diff --git a/temporalio/sig/temporalio/internal/proto_utils.rbs b/temporalio/sig/temporalio/internal/proto_utils.rbs
index 8163528b..47180ea4 100644
--- a/temporalio/sig/temporalio/internal/proto_utils.rbs
+++ b/temporalio/sig/temporalio/internal/proto_utils.rbs
@@ -51,12 +51,14 @@ module Temporalio
 
       def self.convert_from_payload_array: (
         Converters::DataConverter | Converters::PayloadConverter converter,
-        Array[untyped] payloads
+        Array[untyped] payloads,
+        hints: Array[Object]?
       ) -> Array[Object?]
 
       def self.convert_to_payload_array: (
         Converters::DataConverter | Converters::PayloadConverter converter,
-        Array[Object?] values
+        Array[Object?] values,
+        hints: Array[Object]?
       ) -> Array[untyped]
 
       def self.assert_non_reserved_name: (String | Symbol | nil name) -> void
diff --git a/temporalio/sig/temporalio/internal/worker/workflow_instance.rbs b/temporalio/sig/temporalio/internal/worker/workflow_instance.rbs
index 378eebde..63561199 100644
--- a/temporalio/sig/temporalio/internal/worker/workflow_instance.rbs
+++ b/temporalio/sig/temporalio/internal/worker/workflow_instance.rbs
@@ -91,6 +91,7 @@ module Temporalio
           payload_array: Array[untyped],
           method_name: Symbol?,
           raw_args: bool,
+          arg_hints: Array[Object]?,
           ?ignore_first_param: bool
         ) -> Array[Object?]
 
diff --git a/temporalio/sig/temporalio/internal/worker/workflow_instance/child_workflow_handle.rbs b/temporalio/sig/temporalio/internal/worker/workflow_instance/child_workflow_handle.rbs
index ce0be17c..b55a8ed0 100644
--- a/temporalio/sig/temporalio/internal/worker/workflow_instance/child_workflow_handle.rbs
+++ b/temporalio/sig/temporalio/internal/worker/workflow_instance/child_workflow_handle.rbs
@@ -8,7 +8,8 @@ module Temporalio
             first_execution_run_id: String,
             instance: WorkflowInstance,
             cancellation: Cancellation,
-            cancel_callback_key: Object
+            cancel_callback_key: Object,
+            result_hint: Object?
           ) -> void
 
           def _resolve: (untyped resolution) -> void
diff --git a/temporalio/sig/temporalio/internal/worker/workflow_instance/context.rbs b/temporalio/sig/temporalio/internal/worker/workflow_instance/context.rbs
index 1c1b9b10..e3ffda6e 100644
--- a/temporalio/sig/temporalio/internal/worker/workflow_instance/context.rbs
+++ b/temporalio/sig/temporalio/internal/worker/workflow_instance/context.rbs
@@ -40,7 +40,9 @@ module Temporalio
             cancellation_type: Workflow::ActivityCancellationType::enum,
             activity_id: String?,
             disable_eager_execution: bool,
-            priority: Priority
+            priority: Priority,
+            arg_hints: Array[Object]?,
+            result_hint: Object?
           ) -> Object?
 
           def execute_local_activity: (
@@ -53,7 +55,9 @@ module Temporalio
             local_retry_threshold: duration?,
             cancellation: Cancellation,
             cancellation_type: Workflow::ActivityCancellationType::enum,
-            activity_id: String?
+            activity_id: String?,
+            arg_hints: Array[Object]?,
+            result_hint: Object?
           ) -> Object?
 
           def external_workflow_handle: (String workflow_id, ?run_id: String?) -> ExternalWorkflowHandle
@@ -110,7 +114,9 @@ module Temporalio
             cron_schedule: String?,
             memo: Hash[String | Symbol, Object?]?,
             search_attributes: SearchAttributes?,
-            priority: Priority
+            priority: Priority,
+            arg_hints: Array[Object]?,
+            result_hint: Object?
           ) -> ChildWorkflowHandle
 
           def storage: -> Hash[Object, Object]
@@ -138,7 +144,8 @@ module Temporalio
             id: String,
             signal: Workflow::Definition::Signal | Symbol | String,
             args: Array[Object?],
-            cancellation: Cancellation
+            cancellation: Cancellation,
+            arg_hints: Array[Object]?
           ) -> void
 
           def _signal_external_workflow: (
@@ -146,7 +153,8 @@ module Temporalio
             run_id: String?,
             signal: Workflow::Definition::Signal | Symbol | String,
             args: Array[Object?],
-            cancellation: Cancellation
+            cancellation: Cancellation,
+            arg_hints: Array[Object]?
           ) -> void
         end
       end
diff --git a/temporalio/sig/temporalio/internal/worker/workflow_instance/outbound_implementation.rbs b/temporalio/sig/temporalio/internal/worker/workflow_instance/outbound_implementation.rbs
index ae78b428..e3d55140 100644
--- a/temporalio/sig/temporalio/internal/worker/workflow_instance/outbound_implementation.rbs
+++ b/temporalio/sig/temporalio/internal/worker/workflow_instance/outbound_implementation.rbs
@@ -7,13 +7,15 @@ module Temporalio
 
           def execute_activity_with_local_backoffs: (
             local: bool,
-            cancellation: Cancellation
+            cancellation: Cancellation,
+            result_hint: Object?
           ) { (untyped?) -> Integer } -> Object?
 
           def execute_activity_once: (
             local: bool,
             cancellation: Cancellation,
-            last_local_backoff: untyped?
+            last_local_backoff: untyped?,
+            result_hint: Object?
           ) { (untyped?) -> Integer } -> Object?
 
           def _signal_external_workflow: (
@@ -23,6 +25,7 @@ module Temporalio
             signal: Workflow::Definition::Signal | Symbol | String,
             args: Array[Object?],
             cancellation: Cancellation,
+            arg_hints: Array[Object]?,
             headers: Hash[String, Object?]
           ) -> void
         end
diff --git a/temporalio/sig/temporalio/worker/interceptor.rbs b/temporalio/sig/temporalio/worker/interceptor.rbs
index 4a7d4b80..78053e5b 100644
--- a/temporalio/sig/temporalio/worker/interceptor.rbs
+++ b/temporalio/sig/temporalio/worker/interceptor.rbs
@@ -7,11 +7,14 @@ module Temporalio
         class ExecuteInput
           attr_reader proc: Proc
           attr_reader args: Array[Object?]
+          attr_reader arg_hints: Array[Object]?
+          attr_reader result_hint: Object?
           attr_reader headers: Hash[String, Object?]
 
           def initialize: (
             proc: Proc,
             args: Array[Object?],
+            result_hint: Object?,
             headers: Hash[String, Object?]
           ) -> void
         end
@@ -28,8 +31,9 @@ module Temporalio
 
         class HeartbeatInput
           attr_reader details: Array[Object?]
+          attr_reader detail_hints: Array[Object]?
 
-          def initialize: (details: Array[Object?]) -> void
+          def initialize: (details: Array[Object?], detail_hints: Array[Object]?) -> void
         end
 
         class Outbound
@@ -142,8 +146,10 @@ module Temporalio
           attr_reader cancellation_type: Temporalio::Workflow::ActivityCancellationType::enum
           attr_reader activity_id: String?
           attr_reader disable_eager_execution: bool
-          attr_reader headers: Hash[String, Object?]
           attr_reader priority: Temporalio::Priority
+          attr_reader arg_hints: Array[Object]?
+          attr_reader result_hint: Object?
+          attr_reader headers: Hash[String, Object?]
 
           def initialize: (
             activity: String,
@@ -159,8 +165,10 @@ module Temporalio
             cancellation_type: Temporalio::Workflow::ActivityCancellationType::enum,
             activity_id: String?,
             disable_eager_execution: bool,
-            headers: Hash[String, Object?],
-            priority: Temporalio::Priority
+            priority: Temporalio::Priority,
+            arg_hints: Array[Object]?,
+            result_hint: Object?,
+            headers: Hash[String, Object?]
           ) -> void
         end
 
@@ -175,6 +183,8 @@ module Temporalio
           attr_reader cancellation: Cancellation
           attr_reader cancellation_type: Temporalio::Workflow::ActivityCancellationType::enum
           attr_reader activity_id: String?
+          attr_reader arg_hints: Array[Object]?
+          attr_reader result_hint: Object?
           attr_reader headers: Hash[String, Object?]
 
           def initialize: (
@@ -188,6 +198,8 @@ module Temporalio
             cancellation: Cancellation,
             cancellation_type: Temporalio::Workflow::ActivityCancellationType::enum,
             activity_id: String?,
+            arg_hints: Array[Object]?,
+            result_hint: Object?,
             headers: Hash[String, Object?]
           ) -> void
         end
@@ -205,6 +217,7 @@ module Temporalio
           attr_reader signal: String
           attr_reader args: Array[Object?]
           attr_reader cancellation: Cancellation
+          attr_reader arg_hints: Array[Object]?
           attr_reader headers: Hash[String, Object?]
 
           def initialize: (
@@ -212,6 +225,7 @@ module Temporalio
             signal: String,
             args: Array[Object?],
             cancellation: Cancellation,
+            arg_hints: Array[Object]?,
             headers: Hash[String, Object?]
           ) -> void
         end
@@ -222,6 +236,7 @@ module Temporalio
           attr_reader signal: String
           attr_reader args: Array[Object?]
           attr_reader cancellation: Cancellation
+          attr_reader arg_hints: Array[Object]?
           attr_reader headers: Hash[String, Object?]
 
           def initialize: (
@@ -230,6 +245,7 @@ module Temporalio
             signal: String,
             args: Array[Object?],
             cancellation: Cancellation,
+            arg_hints: Array[Object]?,
             headers: Hash[String, Object?]
           ) -> void
         end
@@ -264,8 +280,10 @@ module Temporalio
           attr_reader cron_schedule: String?
           attr_reader memo: Hash[String | Symbol, Object?]?
           attr_reader search_attributes: SearchAttributes?
-          attr_reader headers: Hash[String, Object?]
           attr_reader priority: Temporalio::Priority
+          attr_reader arg_hints: Array[Object]?
+          attr_reader result_hint: Object?
+          attr_reader headers: Hash[String, Object?]
 
           def initialize: (
             workflow: String,
@@ -285,8 +303,10 @@ module Temporalio
             cron_schedule: String?,
             memo: Hash[String | Symbol, Object?]?,
             search_attributes: SearchAttributes?,
-            headers: Hash[String, Object?],
-            priority: Temporalio::Priority
+            priority: Temporalio::Priority,
+            arg_hints: Array[Object]?,
+            result_hint: Object?,
+            headers: Hash[String, Object?]
           ) -> void
         end
 
diff --git a/temporalio/sig/temporalio/workflow.rbs b/temporalio/sig/temporalio/workflow.rbs
index 2bbdcbad..99c736dd 100644
--- a/temporalio/sig/temporalio/workflow.rbs
+++ b/temporalio/sig/temporalio/workflow.rbs
@@ -31,7 +31,9 @@ module Temporalio
       ?cancellation_type: ActivityCancellationType::enum,
       ?activity_id: String?,
       ?disable_eager_execution: bool,
-      ?priority: Priority
+      ?priority: Priority,
+      ?arg_hints: Array[Object]?,
+      ?result_hint: Object?
     ) -> Object?
 
     def self.execute_child_workflow: (
@@ -52,7 +54,9 @@ module Temporalio
       ?cron_schedule: String?,
       ?memo: Hash[String | Symbol, Object?]?,
       ?search_attributes: SearchAttributes?,
-      ?priority: Priority
+      ?priority: Priority,
+      ?arg_hints: Array[Object]?,
+      ?result_hint: Object?
     ) -> Object?
 
     def self.execute_local_activity: (
@@ -65,7 +69,9 @@ module Temporalio
       ?local_retry_threshold: duration?,
       ?cancellation: Cancellation,
       ?cancellation_type: ActivityCancellationType::enum,
-      ?activity_id: String?
+      ?activity_id: String?,
+      ?arg_hints: Array[Object]?,
+      ?result_hint: Object?
     ) -> Object?
 
     def self.external_workflow_handle: (String workflow_id, ?run_id: String?) -> ExternalWorkflowHandle
@@ -116,7 +122,9 @@ module Temporalio
       ?cron_schedule: String?,
       ?memo: Hash[String | Symbol, Object?]?,
       ?search_attributes: SearchAttributes?,
-      ?priority: Priority
+      ?priority: Priority,
+      ?arg_hints: Array[Object]?,
+      ?result_hint: Object?
     ) -> ChildWorkflowHandle
 
     def self.storage: -> Hash[Object, Object]
@@ -158,6 +166,7 @@ module Temporalio
       attr_accessor retry_policy: RetryPolicy?
       attr_accessor memo: Hash[String | Symbol, Object?]?
       attr_accessor search_attributes: SearchAttributes?
+      attr_accessor arg_hints: Array[Object]?
       attr_accessor headers: Hash[String, Object?]
 
       def initialize: (
@@ -169,6 +178,7 @@ module Temporalio
         ?retry_policy: RetryPolicy?,
         ?memo: Hash[String | Symbol, Object?]?,
         ?search_attributes: SearchAttributes?,
+        ?arg_hints: Array[Object]?,
         ?headers: Hash[String, Object?]
       ) -> void
     end
diff --git a/temporalio/sig/temporalio/workflow/child_workflow_handle.rbs b/temporalio/sig/temporalio/workflow/child_workflow_handle.rbs
index b818abf7..ddce2945 100644
--- a/temporalio/sig/temporalio/workflow/child_workflow_handle.rbs
+++ b/temporalio/sig/temporalio/workflow/child_workflow_handle.rbs
@@ -3,13 +3,15 @@ module Temporalio
     class ChildWorkflowHandle
       def id: -> String
       def first_execution_run_id: -> String
+      def result_hint: -> Object?
 
-      def result: -> Object?
+      def result: (?result_hint: Object?) -> Object?
 
       def signal: (
         Workflow::Definition::Signal | Symbol | String signal,
         *Object? args,
-        ?cancellation: Cancellation
+        ?cancellation: Cancellation,
+        ?arg_hints: Array[Object]?
       ) -> void
     end
   end
diff --git a/temporalio/sig/temporalio/workflow/definition.rbs b/temporalio/sig/temporalio/workflow/definition.rbs
index 0f034683..09268c4e 100644
--- a/temporalio/sig/temporalio/workflow/definition.rbs
+++ b/temporalio/sig/temporalio/workflow/definition.rbs
@@ -4,6 +4,8 @@ module Temporalio
       def self.workflow_name: (String | Symbol workflow_name) -> void
       def self.workflow_dynamic: (?bool value) -> void
       def self.workflow_raw_args: (?bool value) -> void
+      def self.workflow_arg_hint: (*Object hints) -> void
+      def self.workflow_result_hint: (Object hint) -> void
       def self.workflow_failure_exception_type: (*singleton(Exception) types) -> void
       def self.workflow_query_attr_reader: (*Symbol attr_names, ?description: String?) -> void
 
@@ -16,14 +18,17 @@ module Temporalio
         ?description: String?,
         ?dynamic: bool,
         ?raw_args: bool,
-        ?unfinished_policy: HandlerUnfinishedPolicy::enum
+        ?unfinished_policy: HandlerUnfinishedPolicy::enum,
+        ?arg_hints: Object | Array[Object] | nil
       ) -> void
 
       def self.workflow_query: (
         ?name: String | Symbol | nil,
         ?description: String?,
         ?dynamic: bool,
-        ?raw_args: bool
+        ?raw_args: bool,
+        ?arg_hints: Object | Array[Object] | nil,
+        ?result_hint: Object?
       ) -> void
 
       def self.workflow_update: (
@@ -31,7 +36,9 @@ module Temporalio
         ?description: String?,
         ?dynamic: bool,
         ?raw_args: bool,
-        ?unfinished_policy: HandlerUnfinishedPolicy::enum
+        ?unfinished_policy: HandlerUnfinishedPolicy::enum,
+        ?arg_hints: Object | Array[Object] | nil,
+        ?result_hint: Object?
       ) -> void
 
       def self.workflow_update_validator: (Symbol update_method) -> void
@@ -43,9 +50,9 @@ module Temporalio
 
       def self._workflow_definition: -> Info
 
-      def self._workflow_type_from_workflow_parameter: (
+      def self._workflow_type_and_hints_from_workflow_parameter: (
         singleton(Workflow::Definition) | Workflow::Definition::Info | Symbol | String workflow
-      ) -> String
+      ) -> [String, Array[Object]?, Object?]
 
       def self._build_workflow_definition: -> Info
 
@@ -63,6 +70,8 @@ module Temporalio
         attr_reader updates: Hash[String?, Update]
         attr_reader versioning_behavior: Integer?
         attr_reader dynamic_options_method: Symbol?
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
 
         def self.from_class: (singleton(Definition) workflow_class) -> Info
 
@@ -77,7 +86,9 @@ module Temporalio
           ?queries: Hash[String, Query],
           ?updates: Hash[String, Update],
           ?versioning_behavior: Integer?,
-          ?dynamic_options_method: Symbol?
+          ?dynamic_options_method: Symbol?,
+          ?arg_hints: Array[Object]?,
+          ?result_hint: Object?
         ) -> void
 
         def name: -> String?
@@ -89,15 +100,19 @@ module Temporalio
         attr_reader description: String?
         attr_reader raw_args: bool
         attr_reader unfinished_policy: HandlerUnfinishedPolicy::enum
+        attr_reader arg_hints: Array[Object]?
 
-        def self._name_from_parameter: (Workflow::Definition::Signal | String | Symbol) -> String
+        def self._name_and_hints_from_parameter: (
+          Workflow::Definition::Signal | String | Symbol signal
+        ) -> [String, Array[Object]?]
 
         def initialize: (
           name: String?,
           to_invoke: Symbol | Proc,
           ?description: String?,
           ?raw_args: bool,
-          ?unfinished_policy: HandlerUnfinishedPolicy::enum
+          ?unfinished_policy: HandlerUnfinishedPolicy::enum,
+          ?arg_hints: Array[Object]?
         ) -> void
       end
 
@@ -106,14 +121,20 @@ module Temporalio
         attr_reader to_invoke: Symbol | Proc
         attr_reader description: String?
         attr_reader raw_args: bool
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
 
-        def self._name_from_parameter: (Workflow::Definition::Query | String | Symbol) -> String
+        def self._name_and_hints_from_parameter: (
+          Workflow::Definition::Query | String | Symbol query
+        ) -> [String, Array[Object]?, Object?]
 
         def initialize: (
           name: String?,
           to_invoke: Symbol | Proc,
           ?description: String?,
-          ?raw_args: bool
+          ?raw_args: bool,
+          ?arg_hints: Array[Object]?,
+          ?result_hint: Object?
         ) -> void
       end
 
@@ -124,8 +145,12 @@ module Temporalio
         attr_reader raw_args: bool
         attr_reader unfinished_policy: HandlerUnfinishedPolicy::enum
         attr_reader validator_to_invoke: Symbol | Proc | nil
+        attr_reader arg_hints: Array[Object]?
+        attr_reader result_hint: Object?
 
-        def self._name_from_parameter: (Workflow::Definition::Update | String | Symbol) -> String
+        def self._name_and_hints_from_parameter: (
+          Workflow::Definition::Update | String | Symbol update
+        ) -> [String, Array[Object]?, Object?]
 
         def initialize: (
           name: String?,
@@ -133,7 +158,9 @@ module Temporalio
           ?description: String?,
           ?raw_args: bool,
           ?unfinished_policy: HandlerUnfinishedPolicy::enum,
-          ?validator_to_invoke: Symbol | Proc | nil
+          ?validator_to_invoke: Symbol | Proc | nil,
+          ?arg_hints: Array[Object]?,
+          ?result_hint: Object?
         ) -> void
 
         def _with_validator_to_invoke: (Symbol | Proc | nil validator_to_invoke) -> Update
diff --git a/temporalio/sig/temporalio/workflow/external_workflow_handle.rbs b/temporalio/sig/temporalio/workflow/external_workflow_handle.rbs
index 4142fefb..762ca16e 100644
--- a/temporalio/sig/temporalio/workflow/external_workflow_handle.rbs
+++ b/temporalio/sig/temporalio/workflow/external_workflow_handle.rbs
@@ -7,7 +7,8 @@ module Temporalio
       def signal: (
         Workflow::Definition::Signal | Symbol | String signal,
         *Object? args,
-        ?cancellation: Cancellation
+        ?cancellation: Cancellation,
+        ?arg_hints: Array[Object]?
       ) -> void
 
       def cancel: -> void
diff --git a/temporalio/test/worker_workflow_test.rb b/temporalio/test/worker_workflow_test.rb
index f5692864..e9184fc1 100644
--- a/temporalio/test/worker_workflow_test.rb
+++ b/temporalio/test/worker_workflow_test.rb
@@ -1786,16 +1786,16 @@ def test_workflow_buffered_metrics
   end
 
   class FailWorkflowPayloadConverter < Temporalio::Converters::PayloadConverter
-    def to_payload(value)
+    def to_payload(value, hint: nil)
       if value == 'fail-on-this-result'
         raise Temporalio::Error::ApplicationError.new('Intentional error', type: 'IntentionalError')
       end
 
-      Temporalio::Converters::PayloadConverter.default.to_payload(value)
+      Temporalio::Converters::PayloadConverter.default.to_payload(value, hint:)
     end
 
-    def from_payload(payload)
-      value = Temporalio::Converters::PayloadConverter.default.from_payload(payload)
+    def from_payload(payload, hint: nil)
+      value = Temporalio::Converters::PayloadConverter.default.from_payload(payload, hint:)
       if value == 'fail-on-this'
         raise Temporalio::Error::ApplicationError.new('Intentional error', type: 'IntentionalError')
       end
@@ -2329,6 +2329,198 @@ def test_no_local_activity
     end
   end
 
+  class HintTrackingJSONConverter < Temporalio::Converters::PayloadConverter::JSONPlain
+    attr_accessor :outbound_hints, :inbound_hints
+
+    def to_payload(value, hint: nil)
+      (@outbound_hints ||= []) << { value:, hint: }
+      super
+    end
+
+    def from_payload(payload, hint: nil)
+      super.tap { |value| (@inbound_hints ||= []) << { value:, hint: } }
+    end
+  end
+
+  class HintActivity < Temporalio::Activity::Definition
+    activity_arg_hint :activity_arg1, :activity_arg2
+    activity_result_hint :activity_result
+
+    def execute(_arg1, _arg2)
+      'act_result'
+    end
+  end
+
+  class HintWorkflow < Temporalio::Workflow::Definition
+    workflow_arg_hint :workflow_arg1, :workflow_arg2
+    workflow_result_hint :workflow_result
+
+    def execute(_arg1, _arg2)
+      # Complete if we're continued
+      return 'wf_result' if Temporalio::Workflow.info.continued_run_id
+
+      Temporalio::Workflow.execute_activity(HintActivity, 'act_arg1', 'act_arg2', start_to_close_timeout: 10)
+      Temporalio::Workflow.wait_condition { @got_update }
+      raise Temporalio::Workflow::ContinueAsNewError.new('cont_wf_arg1', 'cont_wf_arg2')
+    end
+
+    workflow_signal arg_hints: :signal_arg1
+    def my_signal(_arg1)
+      # No-op
+    end
+
+    workflow_query arg_hints: :query_arg1, result_hint: :query_result
+    def my_query(_arg1)
+      'que_result'
+    end
+
+    workflow_update arg_hints: :update_arg1, result_hint: :update_result
+    def my_update(_arg1)
+      # Start child workflow, send signal to it, wait for completion
+      handle = Temporalio::Workflow.start_child_workflow(HintChildWorkflow, 'child_wf_arg1')
+      handle.signal(HintChildWorkflow.my_signal, 'child_sig_arg1')
+      handle.result
+      @got_update = true
+      'upd_result'
+    end
+  end
+
+  class HintChildWorkflow < Temporalio::Workflow::Definition
+    workflow_arg_hint :child_workflow_arg1
+    workflow_result_hint :child_workflow_result
+
+    def execute(_arg1)
+      Temporalio::Workflow.wait_condition { @got_signal }
+      'child_wf_result'
+    end
+
+    workflow_signal arg_hints: :child_signal_arg1
+    def my_signal(_arg1)
+      @got_signal = true
+    end
+  end
+
+  class HintWithStartWorkflow < Temporalio::Workflow::Definition
+    # Intentionally one less hint than args and no result hint
+    workflow_arg_hint :with_start_arg1
+
+    def execute(_arg1, _arg2)
+      Temporalio::Workflow.wait_condition { @result }
+    end
+
+    workflow_signal arg_hints: :with_start_signal_arg1
+    def my_signal(_arg1)
+      @result = 'sig_with_start_wf_result'
+    end
+
+    # Intentionally no arg hint
+    workflow_update result_hint: :with_start_update_result
+    def my_update(_arg1)
+      @result = 'upd_with_start_wf_result'
+      'upd_with_start_upd_result'
+    end
+  end
+
+  def test_hints
+    # New client with tracking JSON converter
+    conv = HintTrackingJSONConverter.new
+    client = Temporalio::Client.new(**env.client.options.with(
+      data_converter: Temporalio::Converters::DataConverter.new(
+        payload_converter: Temporalio::Converters::PayloadConverter::Composite.new(
+          *Temporalio::Converters::PayloadConverter.default.converters.values.map do |c|
+            c.is_a?(Temporalio::Converters::PayloadConverter::JSONPlain) ? conv : c
+          end
+        )
+      )
+    ).to_h)
+    @expected_outbound_hints = []
+    @expected_inbound_hints = []
+
+    # Start worker
+    task_queue = "tq-#{SecureRandom.uuid}"
+    Temporalio::Worker.new(client:, task_queue:,
+                           workflows: [HintWorkflow, HintChildWorkflow, HintWithStartWorkflow],
+                           activities: [HintActivity]).run do
+      # Run workflow
+      wf_hints = [{ value: 'wf_arg1', hint: :workflow_arg1 },
+                  { value: 'wf_arg2', hint: :workflow_arg2 },
+                  { value: 'wf_result', hint: :workflow_result }]
+      act_hints = [{ value: 'act_arg1', hint: :activity_arg1 },
+                   { value: 'act_arg2', hint: :activity_arg2 },
+                   { value: 'act_result', hint: :activity_result }]
+      @expected_outbound_hints.push(*wf_hints, *act_hints)
+      @expected_inbound_hints.push(*wf_hints, *act_hints)
+      handle = client.start_workflow(
+        HintWorkflow,
+        'wf_arg1', 'wf_arg2',
+        id: "wf-#{SecureRandom.uuid}", task_queue:
+      )
+
+      # Send messages
+      msg_hints = [{ value: 'sig_arg1', hint: :signal_arg1 },
+                   { value: 'que_arg1', hint: :query_arg1 },
+                   { value: 'que_result', hint: :query_result },
+                   { value: 'upd_arg1', hint: :update_arg1 },
+                   { value: 'upd_result', hint: :update_result }]
+      @expected_outbound_hints.push(*msg_hints)
+      @expected_inbound_hints.push(*msg_hints)
+      handle.signal(HintWorkflow.my_signal, 'sig_arg1')
+      assert_equal 'que_result', handle.query(HintWorkflow.my_query, 'que_arg1')
+      assert_equal 'upd_result', handle.execute_update(HintWorkflow.my_update, 'upd_arg1')
+
+      # Other things that happened
+      child_hints = [{ value: 'child_wf_arg1', hint: :child_workflow_arg1 },
+                     { value: 'child_sig_arg1', hint: :child_signal_arg1 },
+                     { value: 'child_wf_result', hint: :child_workflow_result }]
+      cont_hints = [{ value: 'cont_wf_arg1', hint: :workflow_arg1 },
+                    { value: 'cont_wf_arg2', hint: :workflow_arg2 }]
+      @expected_outbound_hints.push(*child_hints, *cont_hints)
+      @expected_inbound_hints.push(*child_hints, *cont_hints)
+
+      # Check result
+      assert_equal 'wf_result', handle.result
+
+      # Signal with start
+      sig_with_start_hints = [{ value: 'sig_with_start_wf_arg1', hint: :with_start_arg1 },
+                              { value: 'sig_with_start_wf_arg2', hint: nil },
+                              { value: 'sig_with_start_sig_arg1', hint: :with_start_signal_arg1 },
+                              { value: 'sig_with_start_wf_result', hint: nil }]
+      @expected_outbound_hints.push(*sig_with_start_hints)
+      @expected_inbound_hints.push(*sig_with_start_hints)
+      start_workflow_operation = Temporalio::Client::WithStartWorkflowOperation.new(
+        HintWithStartWorkflow, 'sig_with_start_wf_arg1', 'sig_with_start_wf_arg2',
+        id: "wf-#{SecureRandom.uuid}", task_queue:
+      )
+      client.signal_with_start_workflow(
+        HintWithStartWorkflow.my_signal, 'sig_with_start_sig_arg1',
+        start_workflow_operation:
+      )
+      assert_equal 'sig_with_start_wf_result', start_workflow_operation.workflow_handle.result
+
+      # Update with start
+      upd_with_start_hints = [{ value: 'upd_with_start_wf_arg1', hint: :with_start_arg1 },
+                              { value: 'upd_with_start_wf_arg2', hint: nil },
+                              { value: 'upd_with_start_upd_arg1', hint: nil },
+                              { value: 'upd_with_start_upd_result', hint: :with_start_update_result },
+                              { value: 'upd_with_start_wf_result', hint: nil }]
+      @expected_outbound_hints.push(*upd_with_start_hints)
+      @expected_inbound_hints.push(*upd_with_start_hints)
+      start_workflow_operation = Temporalio::Client::WithStartWorkflowOperation.new(
+        HintWithStartWorkflow, 'upd_with_start_wf_arg1', 'upd_with_start_wf_arg2',
+        id: "wf-#{SecureRandom.uuid}", task_queue:, id_conflict_policy: Temporalio::WorkflowIDConflictPolicy::FAIL
+      )
+      assert_equal 'upd_with_start_upd_result', client.execute_update_with_start_workflow(
+        HintWithStartWorkflow.my_update, 'upd_with_start_upd_arg1',
+        start_workflow_operation:
+      )
+      assert_equal 'upd_with_start_wf_result', start_workflow_operation.workflow_handle.result
+    end
+
+    # Check hints
+    assert_equal @expected_outbound_hints.to_set, conv.outbound_hints.to_set
+    assert_equal @expected_inbound_hints.to_set, conv.inbound_hints.to_set
+  end
+
   class NonDurableTimerWorkfow < Temporalio::Workflow::Definition
     def execute
       sleep(0.1)