MCP Inspector CLI 2.13.0 debugs Claude Code Connection closed errors

The author demonstrates how to use the MCP Inspector CLI to diagnose and debug common Model Context Protocol server startup failures that otherwise produce ambiguous 'Connection closed' errors across different clients like Claude Code and Codex. By launching the server directly through the Inspector with the same command, arguments, and environment variables, developers can inspect underlying server stderr messages such as missing keys, bad paths, or missing dependencies. The article also reviews tool schema requirements and client timeout behaviors. Open article →