[BUG] Gmail MCP search_threads fails with "Tool execution failed" in Cowork desktop app

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?

Claude Cowork: The search_threads tool in the Gmail MCP connector (gmailmcp.googleapis.com/mcp/v1) consistently returns "Tool execution failed. You can try again." for every query, including the most basic ones such as in:inbox. This has been happening for several days and persists across multiple sessions, computer restarts, and Gmail connector disconnects/reconnects. All other Gmail tools — list_labels, get_thread, and create_draft — continue to work correctly, confirming this is not a connectivity or authentication issue but a specific regression in search_threads alone. I am using the Cowork desktop app.

What Should Happen?

search_threads should return matching email threads based on the query provided, consistent with how it functioned before this regression. Results should be returned for standard queries such as in:inbox, sender-based searches, and keyword searches, as is expected from a working Gmail search integration.

Error Messages/Logs

Tool execution failed. You can try again.

Steps to Reproduce

Connect the Gmail MCP connector in the Cowork desktop app
Start a conversation with Claude
Ask Claude to search your Gmail inbox (e.g. "search my inbox for recent emails")
Claude invokes search_threads with any query, including basic ones such as in:inbox with maxResults: 1
Tool returns "Tool execution failed. You can try again." every time regardless of the query used

Expected: Search results returned

Actual: Consistent failure across all queries, all sessions, and after multiple connector reconnects
Sonnet 4.6

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A — using Cowork desktop app, not Claude Code CLI

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_