The Claude Desktop config file is at:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

If that's all you needed, you're done. If you want the full setup guide — how to add MCP servers, common config mistakes, and troubleshooting — keep reading.

I spent two hours staring at Claude Desktop wondering why my MCP server wouldn't connect. The config looked perfect. The server ran fine standalone. But Claude showed no tools. The problem? A single trailing comma in my JSON config that Claude silently ignored. This is everything I wish the docs had told me upfront.

New to MCP? Start with Introduction to MCP to understand what it is and how it works.

My first MCP server took three hours to get working because I made every possible mistake: no logging, broke stdio with print statements, forgot to restart Claude Desktop, and wondered why nothing worked. Your first one should take 30 minutes.

This is what actually works, with the debugging steps I wish I'd known upfront.

I watched Claude hallucinate API endpoints that didn't exist, confidently call made-up functions, and crash our systems with broken JSON. Then we implemented the Model Context Protocol (MCP), and our error rate dropped from 28% to under 3%.

This is what I wish someone had told me when I started.