MCP Inspector is the official debugging tool from the Model Context Protocol team. If you're building or using MCP servers, this is your DevTools equivalent.
Key features:
Zero install: Run with npx, opens in your browser instantly
Server discovery: Auto-detects available tools, resources, and prompts from any MCP server
Interactive testing: Send requests with custom JSON parameters, see full responses
Connection diagnostics: Shows transport details, error messages, and connection state
History: Keeps a log of all requests/responses for debugging sessions
Multiple transports: Supports stdio, SSE, and HTTP transports
Essential for:
Developing custom MCP servers (test before deploying)
Debugging why an MCP tool isn't working in Claude Code or Cursor
Understanding what tools a third-party MCP server provides
Validating MCP server responses match expected schemas
FAQ
Q: Do I need to install anything?
A: No. npx @modelcontextprotocol/inspector runs it directly. No global install needed.
Q: Can I test my own MCP server?
A: Yes. Point it at any MCP server command. It will launch the server, connect via the appropriate transport, and let you interact with it.
Q: Does it work with servers that need environment variables?
A: Yes. You can pass environment variables through the CLI or configure them in the web UI.
Works With
Any MCP server (stdio, SSE, HTTP transport)
Claude Code, Cursor, Windsurf MCP server development