MCP Inspector

When an MCP server misbehaves inside an agent, it is hard to tell whether the problem is the server, the connection, or the model's choices. The MCP Inspector removes the model from the picture. You connect it directly to your server and interact with it yourself.

It is published by the MCP project and is typically run with npx, pointing it at your server's start command or URL. It opens a web interface where you can see the tools the server advertises, read their descriptions and schemas, call them with arguments you choose, and inspect the raw responses.

Use it early and often while building a server. If a tool fails or returns confusing output in the Inspector, it will fail for the model too, and you get a much faster feedback loop than testing through an agent.