fix(mcp_toolset): Prevent infinite hang on stale MCP connections

[akintunca]

Summary

Fixes MCPToolset hanging indefinitely when MCP server connections become stale after idle periods.

Problem

After the agent sits idle, MCPSessionManager returns cached sessions with stale HTTP/SSE connections. When session.list_tools() is called, it blocks forever instead of timing out or reconnecting, blocking the entire event loop.

Solution

• Recreate MCPSessionManager before each get_tools() call to ensure fresh connections
• Add configurable timeouts for session creation and tool listing (default 15s)
• Add timeout for session cleanup (default 5s)
• Fail fast with clear error messages instead of hanging

Changes

• Modified McpToolset.init() to accept timeout parameters
• Modified McpToolset.get_tools() to recreate session manager and add timeout protection

Testing

Tested with remote MCP servers after 10+ minute idle periods. Previously hung indefinitely, now works correctly with fresh connections on each request.

Fixes #3084

[gemini-code-assist]

Summary of Changes

Hello @akintunca, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the robustness and reliability of the MCPToolset by addressing an issue where stale MCP server connections could lead to indefinite hangs. By implementing a strategy to recreate session managers and introducing configurable timeouts for critical operations, the changes ensure that the system remains responsive and provides clear error feedback, preventing application blocking and improving overall stability.

Highlights

• Problem Resolution: This pull request resolves an issue where the MCPToolset would hang indefinitely when MCP server connections became stale after idle periods, particularly after the agent sat idle.
• Connection Management: To ensure fresh connections and prevent stale sessions, the MCPSessionManager is now recreated before each call to get_tools().
• Configurable Timeouts: New configurable timeout parameters have been introduced for session creation, tool listing, and session cleanup, with default values of 15s, 30s, and 5s respectively, to prevent indefinite blocking.
• Improved Error Handling: The system now fails fast with clear RuntimeError messages upon timeout during session creation or tool listing, instead of silently hanging.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request effectively addresses an infinite hang caused by stale MCP connections by recreating the session manager and adding timeouts. The approach is sound. My review includes two suggestions for improvement: moving the local asyncio import to the top of the file for better code style, and, more importantly, adding logging to an exception handler that currently swallows all errors silently. This will improve debuggability without changing the intended behavior of ignoring errors on close.