UK Mortgage Repayment MCP

Tool-only MCP server for estimating UK repayment mortgage payments in ChatGPT.

Run Locally

npm install
npm run dev

The server listens at:

http://localhost:8787/mcp

Use PORT=9000 npm run dev to choose a different port.

Related MCP server: Real Estate MCP Server

Tool

calculate_mortgage_repayment

Inputs:

• loanAmount: mortgage loan amount in pounds sterling

• annualInterestRatePercent: nominal annual interest rate, for example 5.25

• termYears: whole mortgage term in years

• monthlyOverpayment: optional extra monthly repayment in pounds sterling

Outputs include monthly payment, total paid, total interest, and overpayment impact when provided.

Connect To ChatGPT

For local development, expose the MCP server over HTTPS with a tunnel:

ngrok http 8787

Then add the app in ChatGPT developer mode using the HTTPS URL with /mcp, for example:

https://example.ngrok.app/mcp

Verify

npm test
npm run build
npm run typecheck

You can also test the MCP endpoint with the MCP Inspector:

npx @modelcontextprotocol/inspector@latest --server-url http://localhost:8787/mcp --transport http

The calculation is an estimate for illustration only and is not financial advice.