fix(mcp): expose CallToolResult.isError in MCPToolResult#2059
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Zelys-DFKH wants to merge 1 commit intostrands-agents:mainfrom
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fix(mcp): expose CallToolResult.isError in MCPToolResult#2059Zelys-DFKH wants to merge 1 commit intostrands-agents:mainfrom
Zelys-DFKH wants to merge 1 commit intostrands-agents:mainfrom
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MCP tools can return isError=True to signal an application-level failure (the tool ran but reported an error). This flag was used internally to set MCPToolResult.status="error" but was not preserved in the result, making it impossible for callers to distinguish between an application error (isError=True from the MCP server) and a protocol error (Python exception during invocation). Add isError: NotRequired[bool] to MCPToolResult and populate it from CallToolResult.isError in _handle_tool_result(). The field is only present when True, matching the existing pattern used by structuredContent and metadata. Fixes strands-agents#1670
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Description
MCP tools can return `isError=True` to signal an application-level failure (the tool ran but reported an error). This flag was used internally in `_handle_tool_result()` to set `MCPToolResult.status="error"` but was not preserved in the result, making it impossible for callers to distinguish between:
Both produce `status="error"` today, but they are fundamentally different failure modes.
Changes:
Related Issues
Fixes #1670
Documentation PR
N/A
Type of Change
Bug fix
Testing
Checklist
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