Lints a caller-supplied Universal Commerce Protocol (UCP, from Google and Shopify, announced NRF 2026-01-11, Apache-2.0 spec on GitHub) checkout resource against the schema pinned at tag v2026-04-08 of the published UCP repository. Checks the resource-level required fields, the status enum, ISO 4217 currency form, integer minor-unit amounts, and the exactly-one-subtotal / exactly-one-total rule on the totals breakdown. A payload declaring a version outside the pinned allowlist is never upgraded to conformant; it is reported as version-unknown regardless of how clean the structure otherwise is.
The demo payload below is synthetic and already loaded, so you can press Run without entering anything of your own.
It does not contact a UCP or ACP endpoint, does not create or complete a checkout session, and does not validate payment-instrument or merchant identity beyond the fields present in the pasted resource. A CONFORMANT verdict is a structural-shape result against the pinned schema, not a claim of UCP platform certification.
ART-12 checks ACP checkout-session conformance and ART-01 validates the AP2 payment mandate chain. Together with this node they form the Agentic Commerce Convergence chain, binding UCP discovery/cart, ACP checkout, and AP2 payment authorization into one composite receipt.
Copy this paragraph into Claude, OpenClaw, or any MCP-aware agent to run this exact tool, with this sample, and verify the artifact.
Run the AINumbers MCP tool `lint_ucp_checkout_payload`. Task: Deterministic, verify-only structural lint of a caller-supplied Universal Commerce Protocol (UCP; Google + Shopify, announced NRF 2026-01-11, Apache-2.0 spec on GitHub) checkout resource against the schema pinned at tag v2026-04-08 of github.com/Universal-Commerce-Protocol/ucp.
Call it with arguments: {"policy_parameters":{"payload":{"ucp":{"version":"2026-04-08"},"id":"checkout_abc123","status":"ready_for_complete","currency":"USD","line_items":[{"id":"li_1","item":{"id":"sku_1","name":"Widget"},"quantity":2,"totals":[{"type":"subtotal","amount":4000},{"type":"total","amount":4000}]}],"totals":[{"type":"subtotal","amount":4000},{"type":"tax","amount":320,"display_text":"Sales tax"},{"type":"total","amount":4320}],"links":[{"url":"https://merchant.example/tos","type":"terms_of_service"}]}}}
Verify before trusting: call `verify_execution_hash` on mcp.ainumbers.co (https://mcp.ainumbers.co/mcp) with the parameter `claimed_hash` set to the returned `execution_hash`, passing the full artifact the run returned (the object containing `policy_parameters` + `output_payload` + `execution_hash`; equivalently `policy_parameters` + `output_payload` with `claimed_hash`), not the bare hash string.
Return the ledger link https://ledger.ainumbers.co/ so a human can re-verify without contacting us.
PII rule: All inputs are processed locally in your browser. No data is transmitted. Do not enter real personal data — use synthetic or anonymised inputs only.
Open the tool with the sample prefilled: https://ainumbers.co/chaingraph/art-564-ucp-checkout-payload-lint.html#p=v1.H4sIAAAAAAAA_wHcASP-eyJwYXlsb2FkIjp7InVjcCI6eyJ2ZXJzaW9uIjoiMjAyNi0wNC0wOCJ9LCJpZCI6ImNoZWNrb3V0X2FiYzEyMyIsInN0YXR1cyI6InJlYWR5X2Zvcl9jb21wbGV0ZSIsImN1cnJlbmN5IjoiVVNEIiwibGluZV9pdGVtcyI6W3siaWQiOiJsaV8xIiwiaXRlbSI6eyJpZCI6InNrdV8xIiwibmFtZSI6IldpZGdldCJ9LCJxdWFudGl0eSI6MiwidG90YWxzIjpbeyJ0eXBlIjoic3VidG90YWwiLCJhbW91bnQiOjQwMDB9LHsidHlwZSI6InRvdGFsIiwiYW1vdW50Ijo0MDAwfV19XSwidG90YWxzIjpbeyJ0eXBlIjoic3VidG90YWwiLCJhbW91bnQiOjQwMDB9LHsidHlwZSI6InRheCIsImFtb3VudCI6MzIwLCJkaXNwbGF5X3RleHQiOiJTYWxlcyB0YXgifSx7InR5cGUiOiJ0b3RhbCIsImFtb3VudCI6NDMyMH1dLCJsaW5rcyI6W3sidXJsIjoiaHR0cHM6Ly9tZXJjaGFudC5leGFtcGxlL3RvcyIsInR5cGUiOiJ0ZXJtc19vZl9zZXJ2aWNlIn1dfX0PvP4b3AEAAA