MCP ConfigsApr 1, 2026·2 min read

MCP Inspector — Debug MCP Servers Visually

Official MCP Inspector for testing and debugging MCP servers. 9.3K+ stars. Web UI, tool/resource/prompt inspection, request testing.

MC
MCP Hub · Community
Quick Use

Use it first, then decide how deep to go

This block should tell both the user and the agent what to copy, install, and apply first.

npx @modelcontextprotocol/inspector

Opens a web UI at http://localhost:6274. Connect to any MCP server and:

  1. See all available tools, resources, and prompts
  2. Send test requests with custom parameters
  3. View full request/response JSON
  4. Debug connection issues in real-time

Test a specific server:

npx @modelcontextprotocol/inspector npx -y @modelcontextprotocol/server-filesystem /tmp
Intro

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
  • Node.js 18+, runs in any modern browser
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