MCP & Connectors

How do you inspect and debug MCP servers using MCP Inspector?

QUICK ANSWER

Use the official @modelcontextprotocol/inspector command-line interface tool to inspect capabilities, send test requests, and view the JSON-RPC traffic on stdio-based MCP servers.

Using the Inspector

To run the developer console inspector on a local server, launch the command via npx:

npx @modelcontextprotocol/inspector <your-server-command> [args...]

Example: Inspecting PostgreSQL Server

npx @modelcontextprotocol/inspector npx @modelcontextprotocol/server-postgres --conn postgresql://localhost/dev

This command starts a web interface (defaulting to port http://localhost:5173) where you can interactively invoke tools and inspect logging frames.

Verified against: MCP Inspector v0.4.0