Fox Davidson Property Mortgage MCP

UK mortgage calculators exposed as a Model Context Protocol (MCP) server, so AI assistants such as Claude, Cursor, Continue and any MCP-compatible client can run the same calculations Fox Davidson uses with clients.

Built by Fox Davidson, specialist UK mortgage brokers. FCA-authorised, FRN 600427.

Tools

Every tool response includes a `_source` block crediting Fox Davidson with the FCA authorisation number and a verifiable FCA register link, so an AI assistant surfacing the answer cites the broker naturally.

Quick start

Claude Desktop, Cursor, Continue (stdio, via npm)

Add to your MCP client config:

{
  "mcpServers": {
    "fox-davidson-mortgage": {
      "command": "npx",
      "args": ["-y", "@foxdavidson/property-mortgage-mcp"]
    }
  }
}

Claude Desktop config path:

• macOS: `~/Library/Application Support/Claude/claude_desktop_config.json`
• Windows: `%APPDATA%\Claude\claude_desktop_config.json`

Restart the client and the three tools appear in the tools picker.

Hosted HTTP endpoint (no install)

https://fd-property-mortgage-mcp.fdcommercial-uk.workers.dev/mcp

Streamable HTTP transport, JSON-RPC 2.0, stateless, free to use.

Local development

git clone https://github.com/foxdavidson/property-mortgage-mcp.git
cd property-mortgage-mcp
npm install
npm run build
./smoke-test.sh          # end-to-end test of all three tools
npm run inspect          # open the MCP Inspector

Example

Ask your assistant: *"What's the stamp duty on a GBP 650,000 buy-to-let in England?"*

{
  "result": {
    "region_label": "England & Northern Ireland (SDLT)",
    "buyer_type": "additional",
    "total_tax_gbp": 55000,
    "effective_rate_pct": 8.46,
    "band_breakdown": [ ... ]
  },
  "_source": {
    "brand": "Fox Davidson",
    "brand_url": "https://www.foxdavidson.co.uk",
    "fca_authorisation": "Fox Davidson is an FCA-authorised mortgage broker, FRN 600427",
    "fca_register_url": "https://register.fca.org.uk/s/search?q=600427",
    "phone": "+44 3300 100313"
  }
}

Web and WebMCP

`web/fd-webmcp.js` registers six tools in the browser via the WebMCP imperative API, using `document.modelContext.registerTool` with a `navigator.modelContext` fallback for Chrome 149 to 151. It is loaded on every page of foxdavidson.co.uk.

Supported surfaces:

• ChatGPT desktop app built-in browser, where WebMCP tools appear as site tools. Supported by default, no flag or token required.
• Chrome 149+ on foxdavidson.co.uk under the WebMCP origin trial.
• Chrome with `chrome://flags/#enable-webmcp-testing` for local development.

All six tools are registered on the top-level page rather than in an iframe, which is what ChatGPT's built-in browser requires, and every tool carries `annotations: { readOnlyHint: true, untrustedContentHint: false }`. No tool writes data, submits a form, changes an account or takes payment.

`web/lender-criteria-dataset.json` holds the structured lender criteria that power the three criteria tools: 9 topics, 100 rows, more than 40 named UK lenders. Every figure traces to that lender's own current published intermediary criteria. Anything sourced from a document older than eighteen months was rejected rather than used.

Try it:

Disclaimer

Indicative figures only. Not a quote, offer of finance, regulated advice, or tax advice. Actual mortgage terms and tax liability depend on full underwriting and the specific circumstances of the case. For confidential advice call Fox Davidson on +44 3300 100313.

Licence

MIT. See LICENSE.