When you need to look up the exact parameters and schemas for Xcode's 20 MCP tools, this is your reference doc. It covers input/output formats, required fields, and tool categories so you're not guessing at what BuildProject or XcodeGrep actually expects. The router skill splits setup from workflows from API reference, which makes sense when you're three layers deep in a build loop and just need to know if a field is optional. If you're already using xcrun mcpbridge and hit a "what params does this thing take" moment, this saves you from trial and error or digging through MCP inspector logs.
npx skills add https://github.com/charleswiltgen/axiom --skill axiom-xcode-mcp-ref