Mortgage guidelines for your AI agent.

Zeitro is an AI mortgage workstation for loan officers, brokers and lenders. Its guideline library is open to AI agents: an MCP server and a REST API that return the verbatim text of the agency mortgage guidelines, with the document, version date and page behind every passage. No account or key is needed.

Endpoints

What it covers

The free tools search these documents, as published by each agency:

• Fannie Mae Single Family Selling Guide and Eligibility Matrix
• Freddie Mac Single-Family Seller/Servicer Guide
• HUD Handbook 4000.1 (FHA)
• VA Lender's Handbook, VA Pamphlet 26-7
• USDA HB-1-3555

Results are the guideline text itself. Nothing is generated or summarized by a model on our side: your model reads the passages and answers, with the citation in hand. Lender program guides and lender overlays are not part of the free tools; they are in Zeitro Strata.

Connect over MCP

The MCP server is called Zeitro. It needs no sign-in: wherever your client asks for authentication, choose none. All of its tools are read-only.

Claude Code

claude mcp add --transport http zeitro https://strata-mcp.zeitro.com/mcp

Claude (web and desktop)

Settings → Connectors → Add custom connector, then paste https://strata-mcp.zeitro.com/mcp.

ChatGPT

With developer mode turned on (Settings → Apps & Connectors → Advanced settings), create a connector with the server URL https://strata-mcp.zeitro.com/mcp and no authentication.

Cursor

In ~/.cursor/mcp.json:

{
  "mcpServers": {
    "zeitro": { "url": "https://strata-mcp.zeitro.com/mcp" }
  }
}

VS Code

In .vscode/mcp.json:

{
  "servers": {
    "zeitro": { "type": "http", "url": "https://strata-mcp.zeitro.com/mcp" }
  }
}

Anything else

Any client that speaks MCP over streamable HTTP works. To try the tools by hand, run npx @modelcontextprotocol/inspector and connect to https://strata-mcp.zeitro.com/mcp. A plain JSON-RPC call works too:

curl https://strata-mcp.zeitro.com/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call",
       "params":{"name":"search_guidelines",
                 "arguments":{"question":"FHA student loan monthly payment","lenders":["FHA"],"top_k":1}}}'

Tools

Each tool is also a REST endpoint under https://api.zeitro.com/public/v1 that takes the same parameters as a query string and returns the same JSON. The OpenAPI operationId is the tool name.

Example

curl "https://api.zeitro.com/public/v1/guidelines/search?question=FHA%20student%20loan%20monthly%20payment&lenders=FHA&top_k=1&client=my-agent"

The answer (passage text shortened here):

{
  "question": "FHA student loan monthly payment",
  "documents_searched": 1,
  "passages": [
    {
      "doc_id": "8850a99d7ea73ec3",
      "lender": "FHA",
      "document": "HUD Handbook 4000.1, FHA Single Family Housing Policy Handbook",
      "version": "2026-08-12",
      "page": null,
      "score": 0.9651,
      "text": "## **(2) Standard** \n\nThe Mortgagee must include all Student Loans in the Borrower's liabilities, regardless of the payment type or status of payments. …",
      "truncated": true,
      "cite_as": "HUD Handbook 4000.1 II.A.4.b, version 2026-08-12, page not identified (via Zeitro Strata, https://www.zeitro.com/guidelines/hud-handbook-4000-1/ii-a-4-b?utm_source=agent&utm_medium=my-agent&utm_campaign=api&utm_content=hud-handbook-4000-1)",
      "url": "https://www.zeitro.com/guidelines/hud-handbook-4000-1/ii-a-4-b?utm_source=agent&utm_medium=my-agent&utm_campaign=api&utm_content=hud-handbook-4000-1",
      "source_url": "https://www.hud.gov/hud-partners/single-family-handbook-4000-1"
    }
  ],
  "attribution": "Powered by Zeitro Strata, https://www.zeitro.com/strata?utm_source=agent&utm_medium=my-agent&utm_campaign=api&utm_content=attribution",
  "disclaimer": "Guideline text quoted as published by the agency. The latest published version governs. This is not an underwriting decision.",
  "source": "Zeitro Strata guideline library: agency guides (Fannie Mae, Freddie Mac, FHA, VA, USDA) as published by each agency.",
  "asOf": "2026-11-10T22:41:01Z"
}

When a question or the lenders parameter names a lender, the agency passages still come back, and the answer adds:

"not_included": "Lender guidelines and overlays for UWM are not in the free tier. They are in Zeitro Strata (free account): https://lo.zeitro.com/signup?utm_source=agent&utm_medium=my-agent&utm_campaign=api&utm_content=not-included"

More examples in curl, Python and JavaScript are in github.com/Zeitro/zeitro-mortgage-tools.

What comes back

Every link carries utm_source=agent&utm_medium=<client>&utm_campaign=api, so we can see which agents send people to Zeitro. Over MCP the client is the name your client gives in the MCP handshake. Over REST, pass ?client=your-agent or an X-Client-Name header; otherwise we use the User-Agent.

Errors

Errors have a code, a message and a hint the model can act on:

{
  "error": {
    "code": "invalid_parameter",
    "message": "Missing required parameter: question.",
    "hint": "Parameters of this endpoint: question, lenders, doc_ids, top_k (question required). The OpenAPI description is at https://api.zeitro.com/public/v1/openapi.json."
  }
}

Over MCP the same errors come back as tool results marked isError, so the model sees the hint and can try again.

Limits

Without a key: 30 requests a minute per IP address, MCP and REST together, and a daily total for all free use. Over a limit you get a 429 with rate_limited or daily_limit_reached and a Retry-After header. The daily total counts searches and page reads, not document lists. REST answers can be cached for 5 minutes.

Terms of use

• When you show results to people, credit Zeitro and link to the passage's url, for example with its cite_as or the attribution line.
• Keep the citation (document, version, page) with the guideline text, and do not present the text as your own.
• Do not use the free tools to copy the guideline library in bulk. Write to us if you need more.
• Use of the website and the tools is also subject to the Terms & Conditions.

Free API key

A free API key raises the limits to 120 calls a minute and 2,000 searches and page reads a day. It covers the same tools and the agency guidelines; lender guidelines are in Zeitro Strata. Send it as X-API-Key: zk_… or Authorization: Bearer zk_…. Keys go to work email addresses only.

Data, privacy and disclaimer

The guideline text is quoted as published by each agency; the agencies own their guides, and source_url links to the official version. The latest published version governs. Results are not an underwriting decision, and Zeitro is not a lender.

We log each call with the tool, its parameters and your client name, to run the service, enforce limits and improve search. Do not put borrower names, Social Security numbers or other personal information in a question. See the Privacy Policy. Zeitro is SOC 2 audited.

More in Zeitro Strata

The free tools cover the agency guides. Zeitro Strata, part of the Zeitro workstation, adds lender program guides and overlays, more than 2,000 programs from over 100 mortgage investors, and answers scenario questions in a full conversation with every rule cited. Loan officers can create a free account and try Zeitro Strata, the Pricing Engine and the Digital 1003. Questions about the API: support@zeitro.com.

Also from Zeitro

bluerate (www.bluerate.ai), also from Zeitro, has a free API and MCP server that finds licensed US mortgage loan officers by state, city, ZIP code, loan type or language. See the bluerate developer guide.