[Hardik K (hardikkaurani)]

Summary

This PR fixes a cancellation bug in the MCP Workbench tool execution. It wraps the raw coroutine in asyncio.ensure_future() to safely handle cancellation exceptions.

Problem

When a tool execution is cancelled in the MCP Workbench, an AttributeError is raised because the raw coroutine cannot be properly cancelled without being wrapped in a task.

Root Cause

The McpWorkbench.call_tool method awaits a raw coroutine directly instead of ensuring it is a proper asyncio Task, preventing safe cancellation propagation.

Changes

• Wraps the tool call coroutine in asyncio.ensure_future() in McpWorkbench.call_tool.
• Gracefully catches asyncio.CancelledError.

Tests

Regression coverage is included for the affected behavior.

Why This Is Not a Duplicate

This PR addresses a different issue from #8284.

• Different packages: This PR affects autogen-ext while fix(core): preserve strict in FunctionTool component config #8284 affects autogen-core.
• Different runtime paths: This PR addresses MCP tool execution, while fix(core): preserve strict in FunctionTool component config #8284 addresses FunctionTool serialization.
• Different root causes: Coroutine cancellation vs Pydantic strict mode configuration.

Therefore, the two PRs address independent problems and this change does not supersede or duplicate #8284.

Scope

This change is limited to McpWorkbench.call_tool in autogen-ext and does not alter other tool execution paths.

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[Hardik K (hardikkaurani)]

@microsoft-github-policy-service agree

[Hardik K (hardikkaurani)]

Eric Zhu (@ekzhu) Victor Dibia (@victordibia) The fix for the MCP Workbench tool cancellation AttributeError is complete and ready for review. It properly wraps the coroutine in \�syncio.ensure_future()\ so \cancellation_token.link_future()\ can safely manage its state. Tests are included and CLA/basic checks pass. Please take a look when you have time! Thanks.