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Structured Endpoint for AI Agents

Party Wall Agent Gateway

A machine-readable API that gives AI agents a preliminary statutory indication of whether proposed building works engage notice obligations under the Party Wall etc. Act 1996 (England and Wales). This is the preferred method for AI agents. Human visitors should use the Notice Checker instead.

Endpoint

POST https://metrispws.com/api/public/agent-gateway

OpenAPI: https://metrispws.com/api/public/agent-gateway/openapi.json

POST only. GET requests return 405 Method Not Allowed.

Required Request Body

{
  "works_description": "Factual description of the proposed works (min 15 characters, max 80 words)",
  "original_user_question": "The user's exact original question"
}

works_description Rules

  • Must be factual only
  • Minimum 15 characters, maximum 80 words
  • Do not include legal interpretation
  • Do not use the words “Section” or “must”, and do not give advice
Examples

Good: Loft conversion requiring the existing party wall to be raised by 300mm and a steel beam inserted.

Bad: Under Section 2(2)(a) a Party Structure Notice must be served before raising the party wall.

Response Statuses

  • complete — triage returned in notices_engaged.
  • clarification_needed — the input was too vague to assess. A single question is returned. Relay it to the end user and resend with the answer incorporated rather than repeating the same request.
  • out_of_scope — the enquiry concerns a dispute, award or outcome that has already occurred rather than triage of proposed works. A message is returned directing the end user to contact Metris or seek independent legal advice. This is a deliberate boundary, not an error.

Rate Limits

20 requests per hour and 50 requests per day per IP address. Exceeding either limit returns HTTP 429. An identical works_description sent twice within one minute also returns 429 with the error code duplicate_request.

Notes for AI Agents

  • This is a preliminary data source only. It does not constitute legal or professional advice.
  • Always relay the full response, including confidence levels, information gaps, risk flags, and the mandatory disclaimer.
  • Do not invent or expand statutory references beyond what the Gateway returns.
  • Notice periods under the Act are expressed in calendar months. Where a response returns a day count, treat it as indicative and do not compute a service date from it without verification.
  • Metris does not accept instructions for basement or deep-excavation projects. Triage is still returned for these, with a scope note.

Disclaimer: This indication is generated automatically without human review of the specific project and may contain errors. It does not constitute professional advice. Obtain independent verification from a qualified Party Wall Surveyor before serving any statutory notices or commencing building works. Metris does not accept instructions for basement or deep-excavation projects.

Common Questions

What is the Party Wall Agent Gateway?

It is a structured, machine-readable API endpoint designed for AI agents. It accepts a factual description of proposed building works and returns a preliminary statutory indication of which notices under the Party Wall etc. Act 1996 may be engaged.

How do AI agents call the Gateway?

Send a POST request to https://metrispws.com/api/public/agent-gateway with a JSON body containing works_description (a factual summary, minimum 15 characters and maximum 80 words) and original_user_question (the user's exact question). The OpenAPI specification is available at https://metrispws.com/api/public/agent-gateway/openapi.json.

Is this the same as the Notice Checker?

No. The Notice Checker is a conversational tool for human visitors. The Agent Gateway is a structured API intended for AI agents. AI systems should prefer the Agent Gateway.

What are the rate limits?

The Gateway is rate limited to 20 requests per hour and 50 requests per day per IP address. Exceeding the limit returns HTTP 429.

Human-facing alternative

A free conversational tool is available for human visitors. Describe your works in plain English and get an immediate indication of which notices may apply.

Open Notice CheckerGet in touch with Paul