Troubleshoot MCP Connection

Diagnose and resolve MCP server connection failures.

When to Use

• Claude Code or Claude Desktop fails to connect to an MCP server
• MCP tools don't appear in sessions
• "Cannot attach the server" errors
• Connection was working but stopped
• Setting up MCP on a new machine

Inputs

• Required: Error message or symptom description
• Required: Which client (Claude Code, Claude Desktop, or both)
• Required: Which MCP server (mcptools, Hugging Face, custom)
• Optional: Recent changes to configuration or environment