Gmail MCP integration: 'tool no longer exists' error after upgrade

Description

The Gmail MCP integration (mcp__claude_ai_Gmail__gmail_search_messages) consistently returns the following error when called:

This Google Workspace integration was just upgraded and the tool you tried to call no longer exists. Your tool definitions are stale. Tell the user to reload them (e.g. refresh the page on web, or start a new session in Claude Code) and do not retry this tool call.

Steps to Reproduce

1. Use Claude Code CLI with Gmail integration enabled
2. Call mcp__claude_ai_Gmail__gmail_search_messages with any query
3. Error is returned

What I Tried

• Clearing the session (/clear) and retrying
• Reloading tool definitions via ToolSearch — tools load successfully with full schemas but calls still fail
• Multiple attempts across different session resets

Expected Behavior

Gmail search should return matching messages.

Environment

• Claude Code CLI (macOS, Darwin 25.3.0)
• Model: Claude Opus 4.6
• Date: 2026-04-13