feat: add meta field support to MCP tool results #1237
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These changes look good to me, but @dbschmigelski may want integration tests, as they commented here.
Add support for the _meta field in MCP tool results to enable MCP servers to pass arbitrary metadata alongside tool outputs. This allows tracking of token usage, performance metrics, and other business-specific information. Changes: - Add meta field to MCPToolResult TypedDict - Update _handle_tool_result to extract and pass through meta field - Add comprehensive tests for meta field handling - Handle MCP SDK's _meta field aliasing via model_dump() Closes strands-agents#881
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afarntrog
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This was referenced Dec 17, 2025
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Description
Add support for the _meta field in MCP tool results to enable MCP servers to pass arbitrary metadata alongside tool outputs. This allows tracking of token usage, performance metrics, and other business-specific information.
Changes:
The motivation for this change is similar to how we retain structuredContent from MCP tool responses #528. Metadata, like structuredContent, is not accessible to the Agent. Rather this is useful if you are making a tool call manually, or if you want to access the tool results via Hook. Some MCP tools will send back metadata and it will be on the developer to code how that information made aware to the Agent, if at all.
Related Issues
Closes #881
Documentation PR
Type of Change
New feature
Testing
How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli
hatch run prepareChecklist
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