Check Digit Validator for Gemini CLI

com.gumballtools/check-digit

Validates IBAN/ISBN/EAN/Luhn checksums and finds the one wrong digit

client:Gemini CLI transport:streamable-http tools:1

Install Check Digit Validator in Gemini CLI

~/.gemini/settings.json · windows: %USERPROFILE%\.gemini\settings.json

{
  "mcpServers": {
    "check-digit": {
      "httpUrl": "https://check-digit.gumballtools.com/api/mcp"
    }
  }
}

Gemini expands $VAR and ${VAR} inside env values, so a secret can live in your shell rather than this file. Gemini CLI docs