{"name":"debt-payoff-calculator","description":"Calculates debt payoff timelines and the interest saved by extra payments. Same backend as loan-amortization-calculator, exposed for agents comparing loan payoff months, total interest, and extra-principal scenarios. Use it as a debt payoff calculator, extra payment payoff API, or interest savings calculator.","price":"$0.01","method":"POST","input_schema":{"properties":{"principal":{"type":"number","description":"Initial loan principal."},"annual_rate":{"type":"number","description":"Annual interest rate as percent."},"term_months":{"type":"number","description":"Loan term in months."},"term_years":{"type":"number","description":"Alternative loan term in years when term_months is omitted."},"extra_monthly_payment":{"type":"number","description":"Optional extra monthly principal payment. Default 0."}},"required":["principal","annual_rate"]},"input_example":{"principal":420000,"annual_rate":6.8,"term_years":30,"extra_monthly_payment":250},"output_example":{"calculator":"loan-amortization-calculator","score":74.2,"grade":"strong","recommendation":"Proceed with standard diligence and covenant checks.","metrics":{"total_monthly_payment":2988.51,"payoff_months":300,"total_interest":476553.25},"drivers":[{"name":"debt_service_coverage","score":83.6,"weight":0.3,"note":"1.42x DSCR"}],"warnings":[],"source":"deterministic in-process finance calculator; no upstream API"},"x402_payment_required":true,"x402_facilitator":"https://api.cdp.coinbase.com/platform/v2/x402"}