You add an MCP server to your config. The JSON is valid. The client even says "connected." And then: zero tools. No error. No hint. The official /doctor says nothing is wrong.

If this has happened to you, welcome — the GitHub issues are full of us:

MCP servers fail to connect with npx on Windows — 112 comments

MCP Servers Don't Work with NVM — 182 reactions

Claude Desktop silently drops all tools when a server key contains parentheses