VercatusUcp well known profile
A UCP business publishes a machine-readable profile at /.well-known/ucp with ucp.version (date-based; the current spec is 2026-08-25), ucp.services (REST described in OpenAPI, MCP over JSON-RPC, A2A through an Agent Card, and Embedded), ucp.capabilities named in reverse-domain form (dev.ucp.shopping.checkout, dev.ucp.shopping.cart, dev.ucp.shopping.catalog, dev.ucp.shopping.order, dev.ucp.common.identity_linking, with extensions such as dev.ucp.shopping.fulfillment and dev.ucp.shopping.discount), ucp.payment_handlers and a JWK set for signature verification. The platform (agent side) advertises its own profile in a UCP-Agent header, and both sides use the intersection of capabilities they both declare at the highest shared version. Tagged releases so far: 2026-01-11, 2026-01-23, 2026-04-08 and 2026-08-25.
Sources
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- 3Google Developers Blog · 2026Under the hood: Universal Commerce Protocol (UCP)developers.googleblog.com
AGrade A: official documentation or a standard. A grade describes the provenance of the sources above; it is not a probability that a change will work. The effect basis says how the size of the effect is known: measured by a study, taken from an industry report, only documented without a size, or not quantified.
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