US Mortgage Calculator

by usmortgagecalc.com · remote · no sign-in to list tools · v1.0.1 · published by com.usmortgagecalc

US mortgage calculator and amortization API with 50-state property tax, PMI, and affordability data.

Final · 1Changes · 6

Compare Registry entry

11 tools: 1 do something that can't be undone, 6 change things and 4 only read.

Scanned Oct 21, 2026

Deletes or cancels0Claude Code: deny
Can't be undone1Claude Code: ask: see these tools
Changes things6Claude Code: ask: see these tools
Only reads4Claude Code: allow: see these tools

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

claude mcp add --transport http mortgage https://www.usmortgagecalc.com/mcp

Findings

Matches of fixed checks, with the text they matched.

1 warn

Warncalculate_amortization
The server marks "calculate_amortization" read-only (readOnlyHint: true), and its own name, description or input give the class "irreversible".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The description's first verb is "payment": a word that usually means money moves, which cannot be taken back.
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.

11 tools

Can't be undone 1Sends, pays, publishes or merges: once done, it cannot be taken back.Claude Code: ask

calculate_amortizationPayment-by-payment breakdown of how a loan is repaid, showing the split between principal and interest and the falling balance.1 finding
Why it is in this group
- The description's first verb is "payment": a word that usually means money moves, which cannot be taken back.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "calculate_amortization" read-only (readOnlyHint: true), and its own name, description or input give the class "irreversible".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The description's first verb is "payment": a word that usually means money moves, which cannot be taken back.
  What this check looks for
Description, as the server wrote it
Payment-by-payment breakdown of how a loan is repaid, showing the split between principal and interest and the falling balance. Use granularity 'monthly' for the first years in detail, 'yearly' for a whole-term overview. Also reports how much sooner extra principal pays the loan off.
Annotations the server declares
- title: Build an amortization schedule
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false

Changes things 6Creates or changes something that can be changed back.Claude Code: ask

calculate_affordabilityMaximum affordable home price from income, existing debt payments and available down payment, using the 28/36 qualifying ratios.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
Maximum affordable home price from income, existing debt payments and available down payment, using the 28/36 qualifying ratios. Reports which of the two ratios is the binding constraint, which is the actionable part: a buyer limited by the back-end ratio can raise their budget by clearing debt, one limited by the front-end ratio cannot.
Annotations the server declares
- title: Work out how much house someone can afford
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
calculate_mortgageFull monthly housing cost for a US mortgage: principal and interest, property tax, homeowners insurance, mortgage insurance and HOA dues, plus lifetime totals and payoff timing.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
Full monthly housing cost for a US mortgage: principal and interest, property tax, homeowners insurance, mortgage insurance and HOA dues, plus lifetime totals and payoff timing. Pass a state name to use that state's average property tax rate. This is the right tool for 'what would my payment be on a $400,000 house'.
Annotations the server declares
- title: Calculate a monthly mortgage payment
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
calculate_pmiMortgage insurance for any US loan programme, including the upfront charges most calculators omit.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
Mortgage insurance for any US loan programme, including the upfront charges most calculators omit. Conventional: monthly PMI and the month it cancels at 80% and 78% loan-to-value. FHA: the 1.75% upfront premium, monthly MIP, and whether it runs for the life of the loan or ends after 11 years. VA: the funding fee, tiered by down payment and prior use, and waivers. USDA: guarantee and annual fees.
Annotations the server declares
- title: Calculate mortgage insurance
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
calculate_property_taxAnnual and monthly property tax for a home, using a state's average effective rate.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
Annual and monthly property tax for a home, using a state's average effective rate. Also returns how that state ranks nationally and how its rate compares with the national average. For the mechanics behind the number — assessment basis, caps, exemptions, appeal deadlines — use get_state_mortgage_rules.
Annotations the server declares
- title: Estimate property tax
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
calculate_refinanceWhether refinancing is worth it: the new payment, monthly saving, and how many months it takes to recover closing costs.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
Whether refinancing is worth it: the new payment, monthly saving, and how many months it takes to recover closing costs. Also compares lifetime interest, which catches the common trap where a lower payment costs more overall because the term was reset.
Annotations the server declares
- title: Evaluate a refinance
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
estimate_closing_costsLine-by-line buyer closing costs — lender fees, title, appraisal, transfer taxes, prepaid escrow — plus total cash needed at the table including the down payment.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
Line-by-line buyer closing costs — lender fees, title, appraisal, transfer taxes, prepaid escrow — plus total cash needed at the table including the down payment. Marks which items are worth shopping for and which are fixed by the county, and adds the FHA upfront premium, VA funding fee or USDA guarantee fee where they apply.
Annotations the server declares
- title: Itemise closing costs
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false

Only reads 4Looks things up and changes nothing.Claude Code: allow

calculate_rent_vs_buyCompares renting and buying on net wealth rather than on monthly payment, accounting for equity, appreciation, maintenance, selling costs, and the return a renter earns on money no…No findings
Why it is in this group
- The description's first verb is "compare": a word for reading.
Description, as the server wrote it
Compares renting and buying on net wealth rather than on monthly payment, accounting for equity, appreciation, maintenance, selling costs, and the return a renter earns on money not spent on a down payment. Returns the year buying overtakes renting. The result is highly sensitive to the appreciation and investment-return assumptions, which are returned alongside it.
Annotations the server declares
- title: Compare renting with buying
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
compare_loansCompares two to five loan scenarios and reports which is cheapest by monthly payment and which by lifetime cost, separately, because they frequently are not the same loan.No findings
Why it is in this group
- The name "compare_loans" says "compare": a word for reading.
Description, as the server wrote it
Compares two to five loan scenarios and reports which is cheapest by monthly payment and which by lifetime cost, separately, because they frequently are not the same loan. Use for 15-year versus 30-year, FHA versus conventional, competing lender quotes, or with and without discount points.
Annotations the server declares
- title: Compare loan options side by side
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
get_state_mortgage_rulesHow property tax actually works in one state: how assessed value is derived, any statutory growth cap, the billing cycle, named exemptions such as homestead, the filing deadline, w…No findings
Why it is in this group
- The name "get_state_mortgage_rules" says "get": a word for reading.
Description, as the server wrote it
How property tax actually works in one state: how assessed value is derived, any statutory growth cap, the billing cycle, named exemptions such as homestead, the filing deadline, who hears appeals and the window to file, notable county variation, and a link to the state's own tax authority. Use this when the question is about mechanics or deadlines rather than a dollar amount.
Annotations the server declares
- title: Look up a state's property tax rules
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
list_statesEvery US state with its average effective property tax rate, median home value and estimated annual tax.No findings
Why it is in this group
- The name "list_states" says "list": a word for reading.
Description, as the server wrote it
Every US state with its average effective property tax rate, median home value and estimated annual tax. Sortable, so it answers 'which states have the highest property taxes' directly. Call this to discover valid state names for the other tools.
Annotations the server declares
- title: List all 50 states with property tax rates
- 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 1.0.1. Values in angle brackets are yours to fill in.

claude mcp add --transport http mortgage https://www.usmortgagecalc.com/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": [
      "mcp__mortgage__calculate_rent_vs_buy",
      "mcp__mortgage__compare_loans",
      "mcp__mortgage__get_state_mortgage_rules",
      "mcp__mortgage__list_states"
    ],
    "ask": [
      "mcp__mortgage__calculate_mortgage",
      "mcp__mortgage__calculate_amortization",
      "mcp__mortgage__calculate_pmi",
      "mcp__mortgage__calculate_property_tax",
      "mcp__mortgage__calculate_affordability",
      "mcp__mortgage__calculate_refinance",
      "mcp__mortgage__estimate_closing_costs"
    ],
    "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 mortgage. 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/com.usmortgagecalc/mortgage/changes.xml

An Atom feed. Works in any feed reader or Slack's RSS app.

Anlyon alternative

7 of these tools change something. Run those as governed actions.

Declare what an action changes, and Anlyon puts it under a shared limit, binds every approval to the exact request, and grades the outcome. It works on any HTTPS API you can describe as an action.

Anlyon does not run, proxy or govern this MCP server. A tool your own code calls directly is not routed through Anlyon and is not governed by it.

Import an OpenAPI spec →

Compare with other servers for the same product.

Source: MCP Registry. Synced Oct 21, 2026, 18:10 UTC.

For agents: Markdown · JSON · report this listing