[BUG] Cowork Windows: Gmail connector MCP server not responding after successful OAuth — "Authorization with the MCP server failed"

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 fails to connect after completing OAuth. The connector settings page shows an error banner: "Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support: ofid_6ac219f2e627af8f"

All Gmail MCP tool calls return: "The connector's server isn't responding."

Steps taken before failure:

• Clicked Configure on Gmail connector → completed Google OAuth flow
• Restarted Cowork
• Disconnected and reconnected Gmail connector entirely
• Restarted Cowork again

Error persists through all of the above. Google Drive connector (same Google account) is Connected and working fine.

What Should Happen?

After completing OAuth, the Gmail connector should show "Connected" and MCP tool calls should succeed.

Error Messages/Logs

Error banner in claude.ai/settings/connectors:
"Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support: ofid_6ac219f2e627af8f"

All Gmail MCP tool calls return:
"The connector's server isn't responding."

Steps to Reproduce

1. Open claude.ai/settings/connectors in Cowork on Windows
2. Click Configure next to Gmail
3. Complete Google OAuth flow (grant permissions)
4. Return to connectors page — error banner appears: "Authorization with the MCP server failed"
5. Restart Cowork — error persists
6. Disconnect Gmail connector, reconnect, complete OAuth again
7. Restart Cowork again
8. Attempt any Gmail MCP tool call — returns "The connector's server isn't responding"

Note: Google Drive (same Google account) is connected and working correctly.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Latest (Cowork desktop app, updated 2026-04-14)

Platform

Other

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

This is in the Claude Cowork desktop app (Windows), not the Claude Code CLI. Platform and Terminal fields above don't map cleanly — Platform set to "Other."

The support reference code from the error banner is: ofid_6ac219f2e627af8f

Google Calendar connector has the same issue (also fails to connect). Google Drive on the same Google account works fine, suggesting the issue is specific to the Gmail/Calendar MCP server rather than OAuth generally.