The server inspector

MCP Server Debugging and Testing

• Purpose of the MCP Inspector: The MCP Inspector (provided via the Python SDK) allows developers to test and debug MCP servers directly in a browser without needing to connect them to a live application.
• Setup Procedure:
• Activate the Python environment (refer to the README for the specific command).
• Run the command: mcp dev [server_file_name] (e. g. , mcp dev mcpserver. py).
• The server will start listening on a specific port (e. g. , 6277) and provide a direct access address.
• Access this address in the browser to open the MCP Inspector.
• Using the MCP Inspector:
• Connection: Click the "Connect" button to start the MCP server instance.
• Tool Access: Navigate to the "Tools" section and select "List Tools" to view available server functionalities.
• Live Testing: Use the right-hand panel to manually invoke tools, allowing for live development and verification.
• Testing Tool Functionality (Examples):
• Read Doc Contents Tool: Input a Document ID → Output is the full content of that document.
• Edit Document Tool: Input Document ID + Old String → Input New String → Run tool (Success message is returned; the tool does not return the document content).
• Verification: After editing, use the "Read Doc Contents Tool" again with the same Document ID to confirm the changes were applied correctly.

Takeaways

• The MCP Inspector (via the Python SDK) allows developers to test and debug MCP servers directly in a browser without connecting to a live application.
• To start the debugging process, run the command mcp dev [server_file_name] and access the resulting server address in a browser.
• The Inspector allows users to connect to the server, view available functionalities by selecting "List Tools," and manually invoke tools for live testing.
• Tool functionality verification requires using the "Read Doc Contents Tool" after an edit to confirm that changes were successfully applied.