Muppet Inspector

It is a devtool for testing and debugging MCPs servers.

Usage

npx muppet-kit inspector

Features

• Explorer - Explore the MCP server's capabilities, while leveraging AI to assist you.
• Playground - Test the MCP server with different LLMs and configurations.
• MCP Scan - Scan the MCP server for vulnerabilities and security issues.
• Tracing - Trace the requests and responses between the client and server. Tunneling is also supported for connecting to remote clients.
• History - View the history of requests and responses between the client and server for the current session.

Configuration

You can configure the inspector by creating a muppet.config.js/muppet.config.ts file in the root of your project. The configuration file should export an object with the following properties:

import { defineInspectorConfig } from "muppet-kit";
import { ngrok } from "muppet-kit/tunnel";
import { openai } from "@ai-sdk/openai";

export default defineInspectorConfig({
  // ...
  models: [openai("gpt-4.1-nano")],
  // You can either pass the API key here or have it in .env as NGROK_API_KEY
  tunneling: ngrok(),
});

Credits

The idea for this project was inspired by the official MCP Inspector and their amazing work.