Fox Davidson Property Mortgage MCP (Model Context Protocol Server)

This MCP server exposes UK mortgage calculators as a Model Context Protocol (MCP) server. It provides calculations used by Fox Davidson, including stamp duty, MCOB 3A high-net-worth (HNW) qualification, and bridging loan cost. It supports MCP-compatible clients for running consistent mortgage calculations.

🛠️ Key Features

UK mortgage calculators
Stamp duty calculation (SDLT)
MCOB 3A HNW qualification
Bridging loan cost
Package: @foxdavidson/property-mortgage-mcp (MIT license)

🚀 Use Cases

Run UK mortgage cost calculations from an AI assistant via MCP
Evaluate stamp duty and bridging loan cost scenarios consistently
Check MCOB 3A HNW qualification inputs for mortgage workflows

⚡ Developer Benefits

Standardized access via Model Context Protocol
Tool availability: 3 tools
Compatible with Claude, Cursor, Continue, and other MCP-compatible clients

⚠️ Limitations

Scope is limited to the listed UK mortgage calculation areas (stamp duty, MCOB 3A HNW qualification, bridging loan cost)

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

Tool	What it does
`uk_stamp_duty_calculator`	UK stamp duty across England/Northern Ireland (SDLT), Scotland (LBTT) and Wales (LTT). Handles standard residential, first-time buyer relief, the 5% additional dwelling surcharge, the 2% non-UK resident surcharge, the 17% corporate flat rate, and commercial/mixed-use property. Returns a banded breakdown, total tax and effective rate.
`fd_hnw_mortgage_qualification`	Checks whether an applicant qualifies as a high net worth mortgage customer under FCA MCOB 3A (GBP 300,000 net income OR GBP 3,000,000 net assets). Includes primary residence equity and pension. Single or joint application, with a routing recommendation.
`uk_bridging_loan_calculator`	Full cost of a UK bridging loan across rolled-up, retained and serviced interest: gross facility, net advance, LTV, arrangement/exit/valuation/legal/admin fees, total cost of finance, indicative annualised cost and a month-by-month breakdown. Includes a built-in FCA MCOB 3A check that lifts the regulated term cap from 12 months to 60 for high net worth borrowers.

| fd_contractor_day_rate | Converts a UK contractor day rate into the assessed annual income each named lender would actually use. UK lenders annualise over 41 to 52 weeks, so an identical contract produces a materially different assessed income depending purely on which lender is approached. Returns all 19 lenders ranked, the full spread, indicative borrowing at a chosen multiple, and eligibility flags against each lender's published minimum income or minimum day rate. WebMCP only. | | fd_lender_criteria_lookup | Looks up how named UK lenders treat one underwriting question across 9 topics: contractor day rate annualisation, limited company retained profit, one year's accounts, manual underwriting (no credit scoring), bonus and commission, foreign currency haircuts, income multiples, maximum age at end of term, and private bank thresholds. Partial lender name matching. WebMCP only. | | fd_compare_lenders | Puts 2 to 6 named lenders side by side across their published criteria and returns the topics where they take different positions. WebMCP only. |

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:

json

{
  "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)

code

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

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

Local development

bash

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?"

json

{
  "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: https://www.foxdavidson.co.uk/agent-tools/

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.

property_price_gbp	number	required	Property purchase price in pounds. Example: 750000.
region	string	optional	Tax region. 'england' covers England and Northern Ireland (SDLT). 'scotland' uses LBTT. 'wales' uses LTT.
buyer_type	string	optional	Buyer category. 'standard' is a main residence purchase. 'ftb' is first-time buyer (England/NI relief up to GBP 500k; Scotland FTB to GBP 175k; Wales has no FTB relief). 'additional' triggers the second-home surcharge. 'nonresident' adds the 2% non-UK resident surcharge (England/NI only). 'corporate' applies the 17% flat rate above GBP 500k (England/NI residential) or standard rates plus surcharge below threshold or in Scotland/Wales. 'commercial' uses non-residential bands.

applicant_1	object	required	The primary applicant.
applicant_2	object	optional	Optional. If provided, the tool runs the joint application test which returns each applicant individually plus a joint household aggregate. Most lenders apply the MCOB 3A test per individual customer.

property_value_gbp	number	required	Open market value of the security property in pounds.
existing_charges_gbp	number	optional	Existing mortgages or loans the bridge will repay, in pounds.
additional_funds_gbp	number	optional	Additional cash required beyond clearing existing charges, in pounds.
monthly_rate_pct	number	optional	Monthly interest rate as a percentage, for example 0.75 for 0.75% per month.
interest_structure	string	optional	'rolled' compounds monthly and is paid at exit. 'retained' deducts the full term of interest from the advance upfront. 'serviced' is paid monthly. Retained and serviced cost the same; rolled-up costs more.
term_months	number	optional	Loan term in months.
arrangement_fee_pct	number	optional	Lender arrangement fee as a percentage of the loan.
add_arrangement_fee_to_loan	boolean	optional	Whether the arrangement fee is financed into the gross loan (true) or paid separately in cash (false).
exit_fee_pct	number	optional	Exit fee as a percentage, charged on redemption. Often 0.
exit_fee_on_gross	boolean	optional	Whether the exit fee is charged on the gross loan (true) or the net loan (false).
valuation_fee_gbp	number	optional	Valuation fee in pounds.
legal_fees_gbp	number	optional	Lender and borrower legal fees in pounds.
admin_fees_gbp	number	optional	Admin and other fees in pounds.
regulated	boolean	optional	True if the bridge is secured against a property the borrower lives in or intends to live in (regulated). False for investment or commercial security (unregulated).
annual_net_income_gbp	number	optional	Optional. Borrower annual net income, used for the MCOB 3A high net worth term check. GBP 300,000 or more passes the income limb.
net_assets_gbp	number	optional	Optional. Borrower net assets including main residence equity and pension, minus all debts, used for the MCOB 3A high net worth term check. GBP 3,000,000 or more passes the net assets limb.

io.github.foxdavidson/property-mortgage-mcp