Check Digit Validator for Claude Code

com.gumballtools/check-digit

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

client:Claude Code transport:streamable-http tools:1

Install Check Digit Validator in Claude Code

run in your project directory

claude mcp add --transport http check-digit https://check-digit.gumballtools.com/api/mcp

Adds it for this project only. Append --scope user to make it available everywhere. Claude Code docs