MCP Inspector — Debug and Test MCP Servers

What is MCP Inspector?

MCP Inspector is the official debugging and testing tool for MCP (Model Context Protocol) servers. It provides a web-based UI where you can connect to any MCP server, browse available tools and resources, send test requests, and inspect the full message exchange. Essential for MCP server development and troubleshooting.

Answer-Ready: MCP Inspector is the official MCP server debugging tool by Anthropic. Web UI to connect, browse tools, test requests, and inspect messages for any MCP server. Essential for MCP development and troubleshooting. Part of the official MCP SDK.

Best for: MCP server developers and users debugging MCP connections. Works with: Any MCP server (stdio or SSE transport). Setup time: Under 1 minute.

Core Features

1. Server Connection

# Connect via stdio
npx @modelcontextprotocol/inspector node my-server.js

# Connect via SSE
npx @modelcontextprotocol/inspector --transport sse http://localhost:3000/sse

2. Tool Browser

The web UI shows all tools exposed by the connected MCP server:

• Tool name and description
• Input schema (JSON Schema)
• Required and optional parameters

3. Interactive Testing

1. Select a tool from the list
2. Fill in parameters via form UI
3. Click "Execute"
4. See full request/response JSON

4. Resource Browser

Browse resources and resource templates exposed by the server. Read resource contents directly from the UI.

5. Message Inspector

Full request/response log showing:

• JSON-RPC messages
• Timing information
• Error details and stack traces

Use Cases

FAQ

Q: Do I need to install anything? A: No, npx @modelcontextprotocol/inspector runs without installation.

Q: Does it work with any MCP server? A: Yes, supports both stdio and SSE transports. Works with all standard MCP servers.

Q: Can I use it to test Claude Desktop MCP configs? A: Yes, point it at the same command from your Claude Desktop config to verify the server works correctly.