Agent commerce discovery documents

What we check

We probe four locations: the UCP profile at /.well-known/ucp, the ACP discovery file at /.well-known/acp.json, and Shopify's MCP endpoints /api/mcp and /api/ucp/mcp. For UCP or ACP we also note whether checkout is declared (dev.ucp.shopping.checkout for UCP; a checkout entry in capabilities.services for ACP). These are recent drafts. UCP is at version 2026-08-25 (re-verified 2026-09-18). The ACP discovery file is an unreleased ACP proposal; the latest released ACP spec is dated 2026-04-17. The Shopify endpoints are a vendor convention (docs checked 2026-09-10).

Why it matters

These documents tell an AI shopping agent it can talk to your shop directly, for catalogue search, cart or checkout, instead of reading web pages. Most shops do not publish one yet. If you do, agent clients that support these protocols can find your shop.

How we check

A UCP or ACP document counts only when it answers HTTP 200 with JSON containing ucp.version or protocol.name; an HTML page at that path does not. A Shopify MCP endpoint counts if a GET returns 405 or 400 with a JSON body; 401 and 200 do not. PASS: at least one found. FAIL: all four answered and none found. SKIPPED: probes were refused or answered by bot management and nothing was found, so absence is unconfirmed.

How to fix it

1. If your platform or payment provider supports UCP, publish a profile at /.well-known/ucp, declaring dev.ucp.shopping.checkout if you support agent checkout. Shopify and several payment integrations can generate one.
2. Or publish /.well-known/acp.json and an ACP product feed through your payment provider; Stripe, Adyen and PayPal document ACP support.
3. On Shopify, if /api/mcp and /api/ucp/mcp are missing, check whether a proxy or bot protection blocks those paths.
4. Both specifications are changing; check current versions and paths on ucp.dev and agenticcommerce.dev first.

What good looks like

GET /.well-known/ucp  ->  200, Content-Type: application/json

{
  "ucp": {
    "version": "2026-08-25",
    "services": { ... },
    "capabilities": {
      "dev.ucp.shopping.checkout": [
        { "version": "2026-08-25" }
      ]
    },
    "payment_handlers": { ... }
  }
}

Sources

• Universal Commerce Protocol (UCP) specification
• Agentic Commerce Protocol (ACP)
• Stripe: ACP
• Shopify: agents and Storefront MCP

Read more

• UCP explained

  The Universal Commerce Protocol: the profile a store publishes at /.well-known/ucp, the capabilities it declares there, and the checkout flow from a new basket to a placed order.

• How agents discover what a store offers

  Well-known documents, HTTP Link headers and API catalogs are places where a store can say what it offers, and content signals say how its pages may be used. Their status ranges from Standards Track RFC to proposal.