[BUG] Gmail connector search_threads fails consistently for days

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The Gmail connector's search_threads tool has been failing with "Tool execution failed" for several days (since around 2026-08-26). Even the simplest query (a single word) fails every time. Other Gmail tools like list_labels work fine, so it seems isolated to search_threads specifically. I disconnected and reconnected the Gmail connector, which did not fix it.

What Should Happen?

search_threads should return matching Gmail threads without error, the same way list_labels succeeds.

Error Messages/Logs

Tool execution failed. You can try again.

Steps to Reproduce

1. Connect the Gmail connector
2. Call search_threads with any query (even a single word like "test")
3. The call fails immediately with "Tool execution failed"
4. Other Gmail tools (e.g. list_labels) work fine in the same session

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.221 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_