Connect your AI assistant to MarketCode and value a property

This guide takes you from no account to a valuation with its evidence, inside the assistant you already use. It is one server URL, one sign-in, and then a question. Nothing in it costs a credit.

What you need

An assistant that speaks MCP: Claude (any plan, web or desktop), ChatGPT, Codex, Claude Code, Cursor, VS Code with Copilot, Windsurf or Gemini CLI. An email address for the MarketCode account, which is created the first time you sign in and starts with free credits. No API key: the MCP server signs you in with OAuth, and a key pasted into a client's config is a credential where it leaks.

The server URL, for every client:

https://mcp.marketcode.ai/mcp

Step 1: add the server

Claude. Free, Pro and Max: Customize → Connectors → + → Add custom connector, and enter the URL. Team and Enterprise: Organization settings → Connectors → Add → Custom → Web. Choose Connect and sign in. Then enable it for a chat from + → Connectors.

ChatGPT. Settings → Security and login, turn Developer mode on. Then Plugins → +, enter the name MarketCode, a short description, and the URL. ChatGPT discovers the sign-in itself. Add the plugin to a chat from the tools menu.

Codex. In the terminal: codex mcp add marketcode --url https://mcp.marketcode.ai/mcp then codex mcp login marketcode. In the app or IDE: Settings → MCP servers → Add server → Streamable HTTP, paste the URL, Authenticate.

Claude Code. claude mcp add --transport http marketcode https://mcp.marketcode.ai/mcp, then /mcp in the session, choose MarketCode, Authenticate. Or install the plugin, which adds the server and every skill: /plugin marketplace add robosapien-ai/marketcode-plugin then /plugin install marketcode@marketcode.

Cursor. Put {"mcpServers": {"marketcode": {"url": "https://mcp.marketcode.ai/mcp"}}} in .cursor/mcp.json, then Cursor Settings → MCP → MarketCode → Login.

The steps for VS Code, Windsurf and Gemini CLI are on the MCP page.

Step 2: sign in once

Your client opens a MarketCode sign-in page. Use an email link, Google or Microsoft. You approve one scope, property:read: read-only property data. A connected app cannot see your keys, billing or account, and you can disconnect it at any time under Connected apps in the API & MCP Hub. New accounts receive free credits on first sign-in.

Step 3: ask for a valuation

Type a question in plain English. This one works as written:

Value 12 Lordship Lane, London SE22 8HN. Give me the estimate, the range, how confident you are, the comparables you used, and the twelve-month trend for SE22.

Behind that sentence the assistant calls four tools, all free:

• address_resolve turns the address into its UPRN, the one identifier every other tool keys on.
• valuation_full returns the estimate, the low and high of the range, a trust score, and the comparables with the adjustments made to each.
• property_summary adds the record behind the number: type, tenure, floor area, EPC rating, last sale.
• market_index_series for SE22 gives the repeat-sales index and its twelve-month change, so you can say whether the number sits above or below the district's trend.

The answer names each figure's source and the evidence grade behind the comparables. Where floor area is missing from the record, the range is wider and the trust score lower, and the assistant says so.

Step 4: check what it cost

Open the Hub → Usage. Each call is listed with its credit charge, which for everything above is zero. Calls that charge do so for a stated reason, most often a data licence, and the price is in every tool's description before you call it. A failed call is never charged.

What to try next

• "Show me every sale in that building since 2015." (transactions_by_uprn, free)
• "Is the property in a flood zone or a conservation area?" (property_flood_risk, planning_designations, free)
• "Who owns the freehold?" (ownership_by_title, charged, because HM Land Registry licenses the proprietor record)

To turn this into a repeatable, formatted valuation report with every figure cited, install the valuation skill. It is the same tools in a fixed order, laid out the same way every time.