calculate_mortgage_payment
Use this when you want the monthly cost of buying a home with a fixed-rate mortgage, including escrowed taxes and insurance, or the total interest over the loan. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery. Do not use th...
This record as markdown: /tools/com-tttkmbb-calcgrid/calculate-mortgage-payment.md
What calculate_mortgage_payment does on Calcgrid
AI agents call calculate_mortgage_payment to retrieve information from Calcgrid without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
home_price | number | Yes | Purchase price of the property. |
term_years | number | — | Loan term in years (30 and 15 are the common US terms). Unit: years. |
monthly_hoa | number | — | Monthly homeowners-association or condo fee. |
down_payment | number | — | Cash paid up front; loan_amount = home_price − down_payment. For 20 % of a 250,000 home enter 50000. |
annual_property_tax | number | — | Yearly property tax; one twelfth is added to the monthly payment. |
annual_rate_percent | number | Yes | Fixed note rate in percent; the monthly rate is this / 12. Unit: %. |
annual_home_insurance | number | — | Yearly homeowners insurance premium; one twelfth is added monthly. |
Parameters from the server's own tool schema.
Why calculate_mortgage_payment is rated Low
Even though calculate_mortgage_payment only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
The rule that runs calculate_mortgage_payment safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Calcgrid, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For calculate_mortgage_payment, this is the rule to start with:
calculate_mortgage_payment is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Calcgrid, apply this rule, and every calculate_mortgage_payment call is checked against it from then on.
Questions about calculate_mortgage_payment
Use this when you want the monthly cost of buying a home with a fixed-rate mortgage, including escrowed taxes and insurance, or the total interest over the loan. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery. Do not use this when the loan is adjustable-rate or interest-only, or you only need the payment on a plain loan amount (use loan-payment). What it computes: Computes the monthly principal-and-interest payment of a fixed-rate mortgage from home price, down payment, rate and term, then adds property tax, home insurance and HOA dues to give the full monthly housing payment and lifetime interest. Inputs: home_price (number); down_payment (number, optional); annual_rate_percent (number, %); term_years (number, years, optional); annual_property_tax (number, optional); annual_home_insurance (number, optional); monthly_hoa (number, optional). Complete JSON argument examples: {"home_price":250000,"down_payment":50000,"annual_rate_percent":6,"term_years":30,"annual_property_tax":3000,"annual_home_insurance":1200} | {"home_price":400000,"down_payment":80000,"annual_rate_percent":6.5,"term_years":30} Outputs: loan_amount, loan_to_value_percent [%], monthly_principal_and_interest, monthly_property_tax, monthly_insurance, monthly_hoa_fee, total_monthly_payment, number_of_payments, total_interest, total_of_payments, payoff_summary. Formula: loan_amount = home_price − down_payment; i = annual_rate_percent / 1200; n = 12·term_years; P&I = loan_amount × i / (1 − (1 + i)^−n) (loan_amount / n if i = 0); total_monthly_payment = P&I + annual_property_tax/12 + annual_home_insurance/12 + monthly_hoa. Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/mortgage-payment with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/finance/mortgage-payment.md. It is categorised as a Read tool in the Calcgrid MCP Server, which means it retrieves data without modifying state.
calculate_mortgage_payment accepts 7 parameters: home_price, term_years, monthly_hoa, down_payment, annual_property_tax, annual_rate_percent, annual_home_insurance. Required: home_price, annual_rate_percent. The full parameter table on this page comes from the server's own tool schema.
Register the Calcgrid MCP server in PolicyLayer and add a rule for calculate_mortgage_payment: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Calcgrid. Nothing to install.
calculate_mortgage_payment is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the calculate_mortgage_payment rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for calculate_mortgage_payment. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
calculate_mortgage_payment is provided by the Calcgrid MCP server (https://tttkmbb.com/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
More on Calcgrid, and thousands of servers like it.
This server
Across the catalogue