Gmail MCP connector returns empty error after full re-auth cycle

[louislambert]

Description

The standalone Gmail MCP connector consistently returns "Tool returned error result" with no error message body on every call. This is a silent failure — no details about what went wrong are surfaced to the user.

Steps to Reproduce

1. Gmail connector was previously working fine
2. Started returning empty errors on all tool calls (gmail_get_profile, gmail_search_messages, etc.)
3. Attempted the following fixes — none resolved the issue:
   • Disconnected and reconnected the connector in Claude settings
   • Fully uninstalled and reinstalled the connector
   • Revoked "Claude for Gmail" access from Google Account permissions (myaccount.google.com/permissions)
   • Deleted the connector entirely and re-added it as a new connector
   • Re-authorized through the full Google OAuth consent screen

Expected Behavior

After revoking access from Google's side and adding a fresh connector, the OAuth flow should establish a new valid token and tool calls should succeed.

Actual Behavior

• Every tool call returns: Tool returned error result with an empty error body
• The connector ID (315616fb-0a9d-415c-a9be-bcc5338b1440) appears to persist even after delete + re-add, suggesting the backend is reusing a stale connector instance
• The GWS (Google Workspace) connector's Gmail tools work fine against the same Google account, confirming the issue is specific to the standalone Gmail connector infrastructure, not Google-side auth

Environment

• Claude Code CLI (macOS, Darwin 24.6.0)
• Connector type: Anthropic cloud-managed Gmail connector
• Connector ID: 315616fb-0a9d-415c-a9be-bcc5338b1440

Workaround

Using the GWS connector's Gmail tools (mcp__gws__gmail_users_*) as a fallback — these work correctly with valid auth.

[github-actions]

Found 3 possible duplicate issues:

1. Gmail integration fails to reconnect after disconnect #22698
2. [BUG] Gmail OAuth Flow Hangs at Final Redirect in Claude Desktop #30166
3. [BUG] Slack MCP "Failed to connect" — cannot reconnect after re-authentication #37625

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🤖 Generated with Claude Code

[github-actions]

This issue has been automatically closed as a duplicate of #22698.

If this is incorrect, please re-open this issue or create a new one.

🤖 Generated with Claude Code

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.