Add support for capturing ETag values from Microsoft Graph responses

[JeremyVyska]

Problem Description

Currently, the MCP server doesn't expose HTTP response headers from Microsoft Graph API calls. This creates a significant limitation when trying to update resources that require optimistic concurrency control, such as:

• Planner tasks (mcp_ms365_update-planner-task)
• Planner task details (mcp_ms365_update-planner-task-details)
• Calendar events
• Other Microsoft Graph resources that require ETag values

Current Behavior

• GET operations return JSON response bodies but not HTTP headers
• ETag values are not accessible through the MCP interface
• Update operations fail with 400 errors when trying to use * as ETag value
• Users cannot perform reliable updates to Planner tasks or other resources

Expected Behavior

• Optional access to response headers, particularly ETag values
• Ability to perform proper optimistic concurrency updates
• Backward compatibility with existing tool usage

Use Case Example

Planner Task Updates:

1. Get a Planner task to see current state
2. Need the ETag value from response headers to update it
3. Update the task using the ETag in If-Match header
4. Currently impossible due to missing ETag access

Impact

• Planner task management workflows are severely limited
• Cannot implement robust task update patterns
• Data consistency issues when multiple agents/users work with same resources

Proposed Solution

Add an optional includeHeaders parameter to GET operations that:

• Captures response headers when requested
• Returns ETag values in a standardized format
• Maintains backward compatibility
• Enables proper Microsoft Graph update patterns

This would unlock full Planner task management capabilities and other Microsoft Graph update scenarios.

Technical Details

• Affects: src/graph-client.ts and src/graph-tools.ts
• Backward compatible: Optional parameter, existing usage unchanged
• Response format: Adds _etag field when includeHeaders: true

[github-actions]

🎉 This issue has been resolved in version 0.20.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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