RentBuy.org

by rentbuy.org · remote · no sign-in to list tools · v1.3.1 · published by org.rentbuy

Compare renting and buying a home over 30 years: scenarios, side-by-side comparisons, rent sweeps.

Changes · 4

Compare Registry entry

4 tools: 4 change things.

Scanned Oct 21, 2026

Deletes or cancels0Claude Code: deny
Can't be undone0Claude Code: ask
Changes things4Claude Code: ask: see these tools
Only reads0Claude Code: allow

3 checks matched something in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http rentbuy https://rentbuy.org/api/mcp

Findings

Matches of fixed checks, with the text they matched.

3 warn

Warnrentbuy_run_scenario
The server marks "rentbuy_run_scenario" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "rentbuy_run_scenario" says "run": a word for a change.
What this check looks for
Warnrentbuy_compare_scenarios
The server marks "rentbuy_compare_scenarios" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "rentbuy_compare_scenarios" says "compare": a word for reading.
What this check looks for
Warnrentbuy_open_calculator
The server marks "rentbuy_open_calculator" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "rentbuy_open_calculator" says "open": a word for a change.
What this check looks for

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

4 tools

Changes things 4Creates or changes something that can be changed back.Claude Code: ask

rentbuy_compare_scenariosRuns 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 scena…1 finding
Why it is in this group
- The name "rentbuy_compare_scenarios" says "compare": a word for reading.
- The description's first verb is "run": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "rentbuy_compare_scenarios" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "rentbuy_compare_scenarios" says "compare": a word for reading.
  What this check looks for
Description, as the server wrote it
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.
Annotations the server declares
- title: Compare named rent vs buy scenarios
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
rentbuy_open_calculatorOpens an interactive rent-vs-buy calculator with editable inputs, net-worth charts, a year-by-year report and Monte Carlo sensitivity analysis.1 finding
Why it is in this group
- The name "rentbuy_open_calculator" says "open": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "rentbuy_open_calculator" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "rentbuy_open_calculator" says "open": a word for a change.
  What this check looks for
Description, as the server wrote it
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.
Annotations the server declares
- title: Open the RentBuy.org calculator
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
rentbuy_run_scenarioRuns 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 …1 finding
Why it is in this group
- The name "rentbuy_run_scenario" says "run": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "rentbuy_run_scenario" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "rentbuy_run_scenario" says "run": a word for a change.
  What this check looks for
Description, as the server wrote it
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.
Annotations the server declares
- title: Run a rent vs buy scenario
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
rentbuy_sweepVaries 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 th…No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
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?".
Annotations the server declares
- title: Sweep one or two inputs
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 1.3.1. Values in angle brackets are yours to fill in.

claude mcp add --transport http rentbuy https://rentbuy.org/api/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json

{
  "permissions": {
    "allow": [],
    "ask": [
      "mcp__rentbuy__rentbuy_run_scenario",
      "mcp__rentbuy__rentbuy_compare_scenarios",
      "mcp__rentbuy__rentbuy_sweep",
      "mcp__rentbuy__rentbuy_open_calculator"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as rentbuy. Review it before you use it.

Keep track

Get told when this server's tools change: a new tool, a new description, a new class.

https://anlyon.dev/servers/org.rentbuy/rentbuy/changes.xml

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Source: MCP Registry. Synced Oct 21, 2026, 18:54 UTC.

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