Wrong implementation of MethodToolCallback.validateToolContextSupport

[jcgouveia]

Consider the current implementation of validateToolContextSupport compared from 1.0.0 and 1.0.0-M6

	private void validateToolContextSupport(@Nullable ToolContext toolContext) {
		var isNonEmptyToolContextProvided = toolContext != null && !CollectionUtils.isEmpty(toolContext.getContext());
		var isToolContextAcceptedByMethod = Stream.of(this.toolMethod.getParameterTypes())
			.anyMatch(type -> ClassUtils.isAssignable(type, ToolContext.class));
		if (isToolContextAcceptedByMethod && !isNonEmptyToolContextProvided) {
			throw new IllegalArgumentException("ToolContext is required by the method as an argument");
		}
	}

M6

	private void validateToolContextSupport(@Nullable ToolContext toolContext) {
		var isToolContextRequired = toolContext != null && !CollectionUtils.isEmpty(toolContext.getContext());
		var isToolContextAcceptedByMethod = Stream.of(toolMethod.getParameterTypes())
			.anyMatch(type -> ClassUtils.isAssignable(type, ToolContext.class));
		if (isToolContextRequired && !isToolContextAcceptedByMethod) {
			throw new IllegalArgumentException("ToolContext is not supported by the method as an argument");
		}
	}

1. Both have the same serious bug also refered in The isFunctionalType method of MethodToolVNet Provider is incorrect, resulting in some cases where the tool cannot be registered #3355 , it seems that the writer does not know the semantics of ClassUtils.isAssignable(left, right) => right is assinable to left, so left is the "super" type. All this code has the arguments in incorrect order.

2. More, in the case of a toolContext not being provided, the change in the validation logic now make it fail due to error 1
   M6 : No context
   => isToolContextRequired = false
   => isToolContextRequired && !isToolContextAcceptedByMethod = false => no exception
   1.0.0 : No context
   => isNonEmptyToolContextProvided = false + isNonEmptyToolContextProvided = true (because of error 1)
   => isToolContextAcceptedByMethod && !isNonEmptyToolContextProvided = true
   => exception is thrown !

[sunyuhan1998]

Hi @jcgouveia , I checked the code and I agree with you and pushed a PR to try to fix it :#3478, can you help to review this PR?thanks.

[ilayaperumalg]

@jcgouveia Thanks for reporting the issue and the detailed writeup! Please feel free to contribute your suggestions as pull request as well.

@sunyuhan1998 Thanks for the PR!

[ilayaperumalg]

Hi @jcgouveia @sunyuhan1998, I want to bring up a specific use case into discussion related to the logic applied as part of this change. With this tool context validation check, if a chat client has multiple Method tool callbacks but one of them doesn't need tool context to be processed, with a non-empty tool context value, the validation would fail.

[sunyuhan1998]

Hi @jcgouveia @sunyuhan1998, I want to bring up a specific use case into discussion related to the logic applied as part of this change. With this tool context validation check, if a chat client has multiple Method tool callbacks but one of them doesn't need tool context to be processed, with a non-empty tool context value, the validation would fail.

I think I understand what you mean. I believe the key issue lies in the following code:

spring-ai/spring-ai-model/src/main/java/org/springframework/ai/model/tool/DefaultToolCallingManager.java

Lines 222 to 230 in 5cb5c90

	String toolResult;
	try {
	toolResult = toolCallback.call(toolInputArguments, toolContext);
	}
	catch (ToolExecutionException ex) {
	toolResult = this.toolExecutionExceptionProcessor.process(ex);
	}
	observationContext.setToolCallResult(toolResult);
	return toolResult;

It does not take into account whether the Method of the ToolCallback itself accepts ToolContext as a parameter.

I think we have two ways to solve this issue:

1. Adjust the call(String toolInput, @Nullable ToolContext toolContext) method in MethodToolCallback so that if toolContext is null, it internally converts to a call to call(String toolInput).

2. Modify the DefaultToolCallingManager to determine which call method to invoke based on the actual situation during execution.

I prefer the second approach because the first one violates the definition in the ToolCallback interface, which specifies that toolContext should be non-null in the call(String toolInput, @Nullable ToolContext toolContext) method.

I think I can submit a PR to try to fix this issue, do we need to open a new issue?

[sunyuhan1998]

if a chat client has multiple Method tool callbacks but one of them doesn't need tool context to be processed, with a non-empty tool context value, the validation would fail.

Hi @ilayaperumalg , I have submitted an additional PR #3521 to try and fix the issue, could you help review it?thanks.