Install Model Ruler — AI Cost Calculators for Claude Desktop

Claude Desktop reads mcpServers from claude_desktop_config.json. Restart the app after saving.

Open ~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows, or ~/.config/Claude/claude_desktop_config.json on Linux.
Paste the JSON config below.
Replace placeholder secrets, then restart the client if it does not reload on its own.

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "helphub369-model-ruler": {
      "url": "https://modelruler.dev/mcp?dist=model_everywhere_registry_native_official_registry"
    }
  }
}

Official Claude Desktop docs

Install Model Ruler — AI Cost Calculators for Claude Desktop | MCPpedia