MCP InspectorVerified

@modelcontextprotocol

About MCP Inspector

Visual testing tool for MCP servers

Config

Add this server to your MCP-compatible client using the configuration below.

{
  "mcpServers": {
    "inspector": {
      "command": "npx",
      "args": [
        "@modelcontextprotocol/inspector"
      ]
    }
  }
}

Tools

No tools detected

Fetch the live tool list by running this server in a temporary sandbox using the button above.

Overview

What is MCP Inspector?

MCP Inspector is a developer tool for testing and debugging MCP servers. It consists of a React-based web UI (MCPI) that connects to MCP servers via a Node.js proxy (MCPP) supporting stdio, SSE, and streamable-http transports. It is intended for developers building or debugging MCP server implementations.

How to use MCP Inspector?

Run npx @modelcontextprotocol/inspector to start the UI at http://localhost:6274. To inspect a server from its repository, use npx @modelcontextprotocol/inspector node build/index.js with optional arguments and -e flags for environment variables. A Docker image is also available. Ports can be customized via CLIENT_PORT and SERVER_PORT environment variables.

Key features of MCP Inspector

Interactive web UI for testing MCP servers
Supports stdio, SSE, and streamable-http transports
Bearer token authentication with session tokens
Export server launch configurations as mcp.json
Real-time adjustable timeout settings
Persists configuration across sessions

Use cases of MCP Inspector

Debugging MCP server implementations during development
Testing server tools and resources interactively
Validating server configuration for different transport protocols
Exporting server configurations for use in clients like Cursor or Claude Code

FAQ from MCP Inspector

Is MCP Inspector a network proxy for intercepting traffic?

No, it functions as both an MCP client and an HTTP server, enabling browser-based interaction with MCP servers via different transport protocols.

What are the runtime requirements?

Node.js version ^22.7.5 is required.

How does authentication work?

The proxy requires a session token (randomly generated) sent as a Bearer token in the Authorization header. The token is shown in the console and can be pre-filled in the UI.

Can I expose the inspector to other devices?

By default it binds only to localhost. Binding to all interfaces (HOST=0.0.0.0) is possible but dangerous because the proxy can spawn local processes.

What transport protocols does the inspector support?

It supports stdio, SSE (Server-Sent Events), and streamable-http transports.

Frequently asked questions

Is MCP Inspector a network proxy for intercepting traffic?

No, it functions as both an MCP client and an HTTP server, enabling browser-based interaction with MCP servers via different transport protocols.

What are the runtime requirements?

Node.js version ^22.7.5 is required.

How does authentication work?

The proxy requires a session token (randomly generated) sent as a Bearer token in the Authorization header. The token is shown in the console and can be pre-filled in the UI.

Can I expose the inspector to other devices?

By default it binds only to localhost. Binding to all interfaces (`HOST=0.0.0.0`) is possible but dangerous because the proxy can spawn local processes.

What transport protocols does the inspector support?

It supports stdio, SSE (Server-Sent Events), and streamable-http transports.

Comments

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