RentBuy.org

Runs 2 to 10 named scenarios side by side and returns each one's winner, year-30 net worth for both households, break-even year and year-1 cash, plus deltas against the first scenario. Each scenario is an independent set of input overrides and one-time costs on top of the site defaults, so name them by what changes ("15-year loan", "rent $4,500"). One call replaces many rentbuy_run_scenario calls.

rentbuy_compare_scenarios

Opens an interactive rent-vs-buy calculator with editable inputs, net-worth charts, a year-by-year report and Monte Carlo sensitivity analysis. Use when the user wants to see or adjust a scenario. Pass the inputs and one-time costs from the scenario being discussed; missing inputs use the site defaults. rentbuy_run_scenario shows the same result card for a single scenario; rentbuy_compare_scenarios and rentbuy_sweep return data only.

rentbuy_open_calculator

Runs one 30-year rent-vs-buy comparison with the rentbuy.org model and returns the winner, the net worth of both households at year 30, the break-even year, totals, year-1 monthly cash and the fully resolved inputs. Hosts that support MCP Apps also show the result card. Give only the inputs you want to change; everything else uses the site defaults. Set detail to "yearly" to also get the 30 year-by-year rows. Use rentbuy_compare_scenarios or rentbuy_sweep instead of calling this repeatedly.

rentbuy_run_scenario

Varies one input (or a grid of two) across a range and returns, for every point, the buyer-minus-renter net worth at year 30 after selling costs, the winner, both net worths and the break-even year, plus the interpolated crossover value where the winner flips for single-parameter sweeps. Give values[] or min, max and steps (2 to 50 per axis, at most 400 grid points). Other inputs come from "base" or the site defaults. Use it for sensitivity questions such as "at what rent does buying win?" or "how does the result change with the mortgage rate?".

rentbuy_sweep