How can you test an MCP server directly from the terminal?

You can test an MCP server by running it with a command like uv run server.py, which makes it listen on stdin and write responses to stdout. You can then paste JSON messages directly into your terminal and see the server's responses immediately. Start with the initialization handshake messages, then send tool call or list requests. The terminal output shows the complete message exchange in raw JSON format. This technique is useful for debugging message formats and verifying that your server handles requests correctly before building a full client.