{"name":"rule_of_72","title":"Rule of 72 Doubling-Time Calculator","category":"finance","description":"Years to double at a rate (72/70/69.3), or the rate needed to double.","price_usd":0.001,"input_schema":{"type":"object","properties":{"annual_rate_pct":{"type":"number","description":"Annual growth rate percent (gives doubling years)"},"years":{"type":"number","description":"Target doubling years (gives required rate)"}},"additionalProperties":false}}