The server inspector

Setup and Access

• Activate your Python environment (check the readme for exact command)
• Run mcp dev mcpserver. py in terminal to start the server
• Server listens on port 6277 with a browser-accessible address provided
• Open the address to access the MCP Inspector tool

MCP Inspector Overview

• Inspector is actively in development, so UI may change over time
• Left sidebar has a Connect button to start your MCP server
• Top menu bar shows available sections: resources, prompts, tools, and others
• Look for the tools section to view implemented tools

Testing Tools

• Click List Tools to see all available tools in your server
• Click on a specific tool to open its configuration panel on the right
• Manually invoke tools by filling in required parameters and clicking Run Tool
• View success/failure responses and returned data directly in the inspector

Practical Testing Example

• Read Doc Contents tool: Input a document ID to retrieve and verify document contents
• Edit Document tool: Input document ID, old string, and replacement string to modify documents
• Note: This tool returns success confirmation, not the full document
• Verify edits by running the read tool again with the same document ID
• String matching is case-sensitive

Benefits

• Debug and test MCP servers without wiring them to real applications
• Perform live development and iteration on server functionality
• Essential tool for validating server implementation during development

Takeaways

• Use mcp dev mcpserver. py to start your server and access the MCP Inspector tool in your browser
• Click List Tools to view all available tools, then click a specific tool to fill in parameters and click Run Tool to test it
• Verify tool behavior by checking responses directly in the inspector (e. g. , run the read tool after an edit to confirm changes)
• String matching in tools is case-sensitive
• The inspector lets you debug and iterate on MCP server functionality without connecting to real applications