UCP services and transports declared

What we check

We read the service entries under ucp.services, such as dev.ucp.shopping. Each entry names one transport: rest, mcp, a2a or embedded. For rest, mcp and a2a the spec requires an endpoint, which must be an https URL and should not end in a slash. An embedded entry has no endpoint. This check looks at the form of each endpoint and does not call it.

Why it matters

Services are how an agent talks to your store: an MCP server, a REST API or an A2A agent. The spec allows an empty services registry, but then an agent has nothing to act through. We hold the same line as UCP Checker and require at least one service.

How we check

PASS: there is at least one entry and every entry is well formed. Some entries can be malformed: no endpoint, an endpoint that is not a URL or not https, a trailing slash, or a transport we do not recognise. Then the score is the share of well-formed entries, and it stays at WARN or above while at least one entry is well formed. FAIL: there are no services, or no entry has a known transport. A profile with no ucp.version also fails, because it declares nothing an agent can use. SKIPPED: there is no profile, we could not read it, or it is not JSON.

How to fix it

1. Declare at least one transport for dev.ucp.shopping under ucp.services, for example MCP or REST.
2. Give each rest, mcp or a2a entry an https endpoint with no trailing slash.

What good looks like

"services": {
  "dev.ucp.shopping": [
    {
      "version": "2026-08-25",
      "spec": "https://ucp.dev/2026-08-25/specification/overview/",
      "transport": "mcp",
      "endpoint": "https://shop.example/api/ucp/mcp",
      "schema": "https://ucp.dev/2026-08-25/services/shopping/mcp.openrpc.json"
    }
  ]
}

Sources

• UCP 2026-08-25 specification: overview
• UCP 2026-08-25 service schema (service.json)
• UCP Checker: how we check

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.

• UCP vs ACP vs MCP vs AP2

  Which part of a purchase UCP, ACP, MCP and AP2 each define, who backs them, what status each specification gives itself, and where they overlap.