[BUG] MCPClient.__exit__ type annotations don't match context-manager protocol

[cogwirrel]

Checks

• I have updated to the latest minor and patch version of Strands
• I have checked the documentation and this is not expected behavior
• I have searched issues and there are no duplicates of my issue

Strands Version

1.38.0

Python Version

3.12

Operating System

Any

Installation Method

pip

Steps to Reproduce

from strands.tools.mcp.mcp_client import MCPClient

client = MCPClient(lambda: streamablehttp_client("http://localhost:8080/mcp"))
with client:
    pass

Run ty check (or any strict type checker).

Expected Behavior

No type errors — MCPClient should be a valid context manager per the typing protocol.

Actual Behavior

error[invalid-context-manager]: Object of type `MCPClient` cannot be used with `with` because it does not correctly implement `__exit__`

Additional Context

Runtime behavior is correct. The issue is only in the type annotations on __exit__ and stop() in mcp_client.py.

Possible Solution

Fix the parameter types to match the context-manager protocol:

-    def __exit__(self, exc_type: BaseException, exc_val: BaseException, exc_tb: TracebackType) -> None:
+    def __exit__(self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None) -> None:

Apply the same type[BaseException] | None fix to exc_type in stop().