MCP Inspector is a browser-based application for connecting to Model Context Protocol servers, exploring their exposed tools, and invoking live queries without writing client code. It provides a quick confidence check before an MCP server enters an agent workflow. section 13.3.2
Use it to test a local MCP server incrementally:
- Install Node.js, then launch the inspector with npx @modelcontextprotocol/inspector. section 13.3.2
- Select Streamable HTTP, enter the server URL, choose Via Proxy, and disable authentication when the local server requires none. section 13.3.2
- Connect and confirm the green Connected status before inspecting available tools. section 13.3.2
- Open a tool, supply its inputs, and run it to inspect the returned result. section 13.3.2
c:\Github\building-llm-applications\ch11\mcp-inspector> npx @modelcontextprotocol/inspector
Launch the inspector from a project directory with npx; the command starts the local web interface. section 13.3.2
Testing a weather server
Connect to http://127.0.0.1:8020/accu-mcp-server, select Streamable HTTP and Via Proxy, then open get_weather_conditions. Running it for Penzance, UK displays the current weather conditions and confirms that the tool works as expected. If necessary, substitute localhost for 127.0.0.1. section 13.3.2
Treat MCP Inspector as a validation step rather than a production integration layer: test the server interactively, diagnose connection or tool problems, and integrate it with an agent only after its behavior is clear. section 13.5
