Install Mutagen (mutagen.ru), unofficial 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": {
    "svorobiev-ru-mutagen-ru-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "mutagen-ru-mcp@0.1.0"
      ],
      "env": {
        "MUTAGEN_API_KEY": "YOUR_MUTAGEN_API_KEY",
        "MUTAGEN_BUDGET_RUB": "50",
        "MUTAGEN_AUTO_APPROVE_RUB": "1",
        "MUTAGEN_FREE_ONLY": "0",
        "MUTAGEN_TOOLS": ""
      }
    }
  }
}

Official Claude Desktop docs

Install Mutagen (mutagen.ru), unofficial for Claude Desktop | MCPpedia