Mortgage Calculator Skill

Overview

A mortgage API and payment calculation API for real estate listings, lending tools and budgeting apps. Mortgage Calculator works by using the loan amount, interest rate, and loan term to calculate the monthly mortgage payment and loan-to-value ratio, with total interest paid, PMI and its removal date, payoff dates and extra-payment payoff scenarios on paid plans.

Live Test Mortgage Calculator Skill Skill →

The tool

Once your client is connected to the VerveKit server, this appears in its tool list as MortgageCalculatorSkill. It is read-only and open-world — it fetches and never mutates anything on your side — so most clients call it without asking you to confirm.

{
  "name": "MortgageCalculatorSkill",
  "arguments": {
    "amount": "200000",
    "rate": "4.5",
    "years": "30"
  }
}

You do not name the tool yourself; the model picks it. Asking about 200000 in the terms this skill covers is enough for it to reach for MortgageCalculatorSkill on its own — naming it explicitly also works, and is the way to force the call.

Connecting

One server URL covers every skill in the catalog, including this one. Authorization is OAuth: the client opens a browser once, and there is no key to paste into a config file.

{
  "mcpServers": {
    "vervekit": {
      "url": "https://api.vervekit.com/v1/mcp"
    }
  }
}

https://api.vervekit.com/v1/mcp

Per-client setup — Claude, Cursor, VS Code, ChatGPT — is on the MCP setup page.

Arguments

These are the properties on the tool's inputSchema, so a well-behaved client validates them before the call is made. Premium arguments are accepted on every plan but only take effect on plans that include them.

What the model gets back

The result carries a structuredContent object matching the tool's declared outputSchema, so a client reads fields without parsing prose. status is "ok" and error is null on success; a null field means the value was not available for that input, not that the call failed.

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{
  "status": "ok",
  "error": null,
  "data": {
    "amount": 570000,
    "downpayment": 57000,
    "rate": 6.8,
    "years": 30,
    "total_interest_paid": 690975.44,
    "total_loan_payment": 1203975.44,
    "interestRatio": 57.39,
    "monthly_payment": {
      "total": 3558.13,
      "mortgage": 3344.38,
      "property_tax": 0,
      "hoa": 0,
      "home_insurance": 0,
      "pmi": 213.75
    },
    "annual_payment": {
      "total": 42697.51,
      "mortgage": 40132.51,
      "property_tax": 0,
      "hoa": 0,
      "home_insurance": 0,
      "pmi": 2565
    },
    "formatted": {
      "amount": "$570,000",
      "monthlyPayment": "$3,344.38",
      "totalInterestPaid": "$690,975.44",
      "totalLoanPayment": "$1,203,975.44"
    },
    "loan_amount": 513000,
    "ltv": 90,
    "payoff_date": "2056-11",
    "pmi": {
      "required": true,
      "rate": 0.5,
      "monthly": 213.75,
      "months_charged": 113,
      "removal_month": 114,
      "total": 24153.75,
      "removal_date": "2036-05"
    },
    "extra_payments": {
      "monthly": 200,
      "months_to_payoff": 304,
      "months_saved": 56,
      "total_interest_paid": 563208.85,
      "interest_saved": 127766.58,
      "payoff_date": "2052-03"
    },
    "amortization_schedule": [
      {
        "month": 1,
        "interest_payment": 2907,
        "principal_payment": 437.38,
        "remaining_balance": 512562.62,
        "date": "2026-12"
      },
      {
        "month": 2,
        "interest_payment": 2904.52,
        "principal_payment": 439.85,
        "remaining_balance": 512122.77,
        "date": "2027-01"
      },
      {
        "month": 3,
        "interest_payment": 2902.03,
        "principal_payment": 442.35,
        "remaining_balance": 511680.42,
        "date": "2027-02"
      }
    ]
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Failure modes

Errors come back as tool errors carrying a sentence the model can act on, not a bare status code. Error handling covers the full list.

A call costs 2 credits each time the tool actually runs; a model that reasons about the tool without calling it costs nothing.

Use cases

Listing Affordability Estimates

Real estate portals display estimated monthly costs, factoring in local taxes and HOA dues beside listing sale prices.

Mortgage Offer Comparisons

When prospective borrowers evaluate competing quotes, financial platforms run side-by-side payment breakdowns across differing interest rates and terms.

Budget Planning Applications

To assess homeownership readiness, personal finance apps calculate prospective monthly housing obligations against user savings and down payment targets.

Client Payment Previews

Mortgage brokers quote projected monthly housing dues to prospective buyers during initial consultations before submitting formal underwriting applications.

Other ways to use Mortgage Calculator Skill

Set up Mortgage Calculator Skill on VerveKit, or reach the same source a different way. Your VerveKit account and credits work on all of them — one key, one balance.

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