* feat(mcp): add per-server tool_call_timeout for MCP tool calls
Add a configurable timeout for individual MCP tool calls to prevent
agent runs from blocking indefinitely when an MCP server becomes
unresponsive (e.g., rate-limited HTTP API, hung subprocess).
Uses the MCP SDK's built-in read_timeout_seconds parameter on
ClientSession.call_tool, which handles the timeout within the
session's own task — avoiding cross-task cancellation issues with
the session pool (ref #3379, #3203).
Config field is named tool_call_timeout (not timeout) to avoid
collision with langchain-mcp-adapters' existing timeout field on
HTTP/SSE connections.
Closes#3840
* fix(mcp): read tool_call_timeout from McpServerConfig, not connection dict
The previous implementation put tool_call_timeout into the connection dict
returned by build_server_params, which langchain's create_session then
passed to _create_stdio_session(), causing TypeError. Now reads the timeout
directly from ExtensionsConfig.mcp_servers where the wrapper is built,
keeping it out of the connection dict entirely.
Fixes P1 bug from review on #3843.
* test(mcp): regression test for tool_call_timeout not leaking into connection dict
Adds two tests:
- test_build_server_params_excludes_tool_call_timeout: verifies the connection
dict returned by build_server_params() does NOT contain tool_call_timeout
- test_stdio_tool_call_timeout_does_not_raise_typeerror: end-to-end test that
get_mcp_tools() with a stdio server having tool_call_timeout configured loads
tools without TypeError from _create_stdio_session()
Regression for PR #3843 P1 bug.
* fix(mcp): only pass read_timeout_seconds when tool_call_timeout is set
When tool_call_timeout is None, don't pass read_timeout_seconds=None to
session.call_tool(). This avoids breaking existing tests that assert on
exact call_tool arguments without the extra kwarg.
* docs(mcp): clarify stdio tool timeout
c9a5f23e7b