28goods.com

Cache-Control max-age is within recommended bounds

No Cache-Control header — clients may re-fetch every request

Profile response advertises cache headers

Discovery response has no Cache-Control header

Profile declares at least the checkout capability

Completed in 102ms

Capability version strings are valid ISO dates

Completed in 91ms

Profile response Content-Type is application/json

Completed in 94ms

Discovery endpoint exposes CORS headers

Completed in 85ms

Profile is served over HTTPS

Completed in 39ms

Two consecutive profile fetches return identical bodies

Completed in 195ms

Signing JWKs use only allowed kty/crv values

Profile declares no signing_keys array — the field is optional per the UCP spec, but agents cannot verify signed payloads from this merchant

No duplicate capability entries (same name + version)

Completed in 96ms

OpenAPI servers[] URL is reachable

Profile has no loadable service-level OpenAPI document

Business profile has a valid structure

Completed in 94ms

Merchant responses are signed with the published signing_keys

Profile declares no signing_keys; nothing to verify against. DISC-0002 tracks absence separately.

robots.txt allows AI agents to read the UCP profile

Completed in 149ms

All declared schema URLs use HTTPS

Completed in 136ms

Signing keys are importable via Web Crypto

Profile declares no signing_keys array — the field is optional per the UCP spec, but agents cannot verify signed payloads from this merchant

Profile advertises well-formed signing keys

Profile declares no signing_keys array — the field is optional per the UCP spec, but agents cannot verify signed payloads from this merchant

Service binding transports are in the allowed set

Completed in 109ms

Profile declares a ucp.version string

Completed in 93ms

Profile ucp.version is one the grader recognizes

Completed in 94ms

Profile is served at the canonical .well-known/ucp path

Completed in 100ms

Declared capabilities match operations in the OpenAPI

No OpenAPI operations available to cross-check

Capability JSON Schemas declare a modern $schema draft

Capability-level JSON Schemas are well-formed

OpenAPI components.schemas has no orphans

Profile has no loadable service-level OpenAPI document

Service-level OpenAPI document is valid OpenAPI 3.x

No service-level OpenAPI schema was loaded

Every OpenAPI operation declares a 2xx JSON response schema

Profile has no loadable service-level OpenAPI document

All declared schema URLs return 200

Discovery profile matches the published JSON Schema

Completed in 106ms

Selected options filter variants in product detail

No product with options/variants found in catalog

Canceling a session twice with the same idempotency key is idempotent

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Cancel a checkout session

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Create checkout session with defaults

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Repeated createSession with same idempotency key returns same session

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Create session then set shipping address

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Retrieve a checkout session by id

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Reusing an Idempotency-Key with a different body must be rejected

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

update_checkout is idempotent on replay and rejects conflicting replays

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Select a shipping method on a checkout session

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Shipping methods are returned after setting an address

Merchant gates checkout creation behind authentication (HTTP 403); cannot probe further without credentials

Catalog capability advertised for product lookup

Catalog capability is declared

Checkout capability is declared and reachable

Completed in 135ms

Fulfillment capability is declared