Searches Calcupedia's 2,400+ calculators and unit converters by keyword (for example "mortgage", "bmi", "kg to lbs"). Returns matching calculators with their slug, category and page link; the top 3 also list their input keys, defaults and allowed values. Use it when the user wants a number worked out (a loan or mortgage payment, interest, savings, tax, salary, BMI, calories, a date or age, a percentage or a unit conversion) or asks for a calculator, then pass the slug to run_calculator.