Protocol specifications and conformance matrix

A dated inventory of what each official project publishes: a specification, machine-readable artifacts, a conformance suite and separate validation tooling.

Reviewed 2026-08-27.

What this proves: a linked artifact was present in the official source reviewed on the date above. It does not prove that this site ran the tool, that an implementation passed, or that no unlisted artifact exists. “Not identified” is a scoped audit result, not a universal absence claim.

Reuse status: no separate reuse license has been published for these exports. Download availability is not presented as a grant of reuse rights.

Execution log

What was actually run

Passed on 2026-08-27: the official mppx discover validate command was run against one valid local document and one deliberately invalid negative control.

Tool version, expected / obtained: 0.9.0 / 0.9.0
Valid fixture exit code, expected / obtained: 0 / 0
Negative-control exit code, expected / obtained: 1 / 1
Reproduction command: node scripts/verify-mpp-discovery.mjs
Fixture integrity: tests/fixtures/mpp/discovery-valid.json: e6cdf00c84253f3433c8e7e674e07fbfa65b5b176100a585bf0eae8c38994c30
tests/fixtures/mpp/discovery-invalid.json: ba30ad324c9ca641a6fdedddeeb7b78f87b133efa0a5dc52ff258c3e2148851d

Limit: This run validates two local OpenAPI discovery documents only. It creates no account, uses no secret, contacts no payment server and transfers no funds. It does not run the separate end-to-end server and payment-flow test, and it does not establish conformance for any third-party implementation. The MCP and A2A suites still require a specific client or server under test before their results can be meaningfully published.

Protocol	Reviewed release	Specification	Machine-readable	Conformance suite or TCK	Official validator	Limit
Universal Commerce Protocol	v2026-08-25	Published	Published	Published	Published	The public suite and schema tooling were inventoried, not executed. The observed Flower Shop fixture and CI target 2026-04-08, so compatibility with v2026-08-25 is not established here.
Agentic Commerce Protocol	2026-04-17	Published	Published	Not identified	Not identified	The official repository publishes OpenAPI, JSON Schema, examples and manual RFC checklists. An official automated conformance suite or validator was not identified in the reviewed sources.
Agent Payments Protocol	v0.2	Published	Published	Not identified	Not identified	The official repository publishes canonical JSON schemas, an SDK and samples. A vendor-neutral conformance suite was not identified in its reviewed overview.
Model Context Protocol	2026-07-28	Published	Published	Published	Not identified	The official repository publishes TypeScript and JSON Schema plus an official client/server conformance framework with frozen requirements for the 2026-07-28 specification. This is not a certification program.
Agent2Agent Protocol	v1.0.0	Published	Published	Published	Not identified	The official project publishes the specification, SDKs, samples and a Technology Compatibility Kit for gRPC, JSON-RPC and HTTP+JSON. The TCK is not presented here as a certification program.
x402	Current main; no dated release asserted	Published	Published	Not identified	Not identified	The official repository contains specifications, SDKs, examples and end-to-end tests. Those project tests are not presented here as a vendor-neutral conformance certification.
Machine Payments Protocol	Launch specification, 2026-03-18	Published	Not identified	Not identified	Published	The protocol requires payment methods to define request and payload schemas, but a separate normative neutral schema bundle was not identified. The official mppx validate command checks servers end to end; it is a validator, not a certification program.
Trusted Agent Protocol	No tagged release asserted	Published	Not identified	Not identified	Not identified	Visa publishes merchant specifications, Pydantic implementation models and a sample system under custom terms. No distinct normative JSON Schema, OpenAPI or protobuf artifact, tagged release, automated conformance suite or validator was identified.
Mastercard Agent Pay	Proprietary program with a public acceptance framework	Not identified	Not identified	Not identified	Not identified	Mastercard publishes a proprietary Agent Pay Acceptance Framework that uses Web Bot Auth and aligns with MCP, A2A and ACP, but not as an autonomous open specification. Verifiable Intent is a separate open-source initiative transferred to FIDO. No Agent Pay normative machine-readable artifact, automated conformance suite or validator was identified.