The Universal Commerce Protocol is composed, not authored. This page maps the standards and protocols that already exist or are actively forming, organizes them by the plane of the stack they cover, and calls out the gaps.
Every standard below is Established, Emerging, Probable or Speculative. Dates are the most recent relevant milestone at time of writing.
The standards map
| Standard | Plane | Maturity | Role |
|---|---|---|---|
| schema.org Product, Offer, AggregateRating | Semantic | Established | Canonical vocabulary for product data on the open web. |
| schema.org MerchantReturnPolicy, ShippingRateSettings | Policy | Emerging (2023+) | Structured expression of returns and shipping. |
| GS1 GTIN | Identity | Established | Global product identifier. |
| GS1 Digital Link | Identity / Discovery | Emerging | Resolvable URLs carrying GS1 identifiers. |
| Google Merchant Center feed spec | Transport | Established | De facto commercial feed spec used beyond Google. |
| OpenAPI / GraphQL | Transport | Established | API description formats for read/write endpoints. |
| MCP (Model Context Protocol) | Agent tooling | Emerging (2024-11) | Standard for exposing tools and resources to LLM agents. |
| A2A (Agent-to-Agent) | Agent tooling | Emerging (2025) | Horizontal communication between agents. |
| OpenAI Apps SDK | Agent tooling / Discovery | Emerging (2025) | Expose apps inside ChatGPT; commerce apps included. |
| Anthropic Claude Skills / MCP servers | Agent tooling | Emerging | Custom tools exposed via MCP to Claude. |
| Stripe Agentic Commerce | Transaction | Emerging (2024 Q4) | Agent-scoped payment intents, spend controls. |
| Visa Intelligent Commerce | Transaction / Identity | Emerging (2025) | Agent-bound card credentials with delegated authority. |
| Mastercard Agent Pay | Transaction / Identity | Emerging (2025) | Agent identity + tokenized credentials. |
| PayPal agent tooling | Transaction | Emerging | Agent endpoints, identity features. |
| llms.txt | Discovery (generic web) | Emerging | Site-level guidance for LLM crawlers. Not commerce-specific. |
| robots.txt + user-agent strings | Discovery | Established | Crawl access controls. Agent operators now declare UAs. |
| Sitemaps (XML) | Discovery | Established | Enumerate canonical URLs for crawlers. |
| Verifiable Credentials / Decentralized Identifiers | Trust | Emerging | Potential substrate for agent identity and merchant claims. |
How the plane composition works
Read this diagram as a stack:
─────────────────────────────────────────────
TRUST Agent identity, merchant claims, provenance
(VC/DID, agent-UA fingerprinting, reviews)
─────────────────────────────────────────────
TRANSACTION Payment rails, order lifecycle
(Stripe ACP, Visa IC, Mastercard Agent Pay)
─────────────────────────────────────────────
POLICY Returns, warranty, shipping, restrictions
(schema.org MerchantReturnPolicy, ShippingRateSettings)
─────────────────────────────────────────────
DISCOVERY How agents find merchants / offers
(Feeds, sitemaps, MCP tools, Apps SDK, marketplaces)
─────────────────────────────────────────────
SEMANTIC Product, offer, variant, attribute meaning
(schema.org Product/Offer, GS1 attributes)
─────────────────────────────────────────────
IDENTITY Product, brand, merchant identifiers
(GTIN, MPN, GLN, GS1 Digital Link)
─────────────────────────────────────────────
No single spec covers all planes. Adoption is stack-by-stack.
Stripe ACP vs Visa IC vs Mastercard Agent Pay
| Stripe Agentic Commerce | Visa Intelligent Commerce | Mastercard Agent Pay | |
|---|---|---|---|
| Actor type | PSP | Card network | Card network |
| Credential | Agent-scoped PaymentIntent | Agent-bound card credential | Tokenized credential with agent identity |
| Merchant impact | Stripe-side, minimal merchant code | Requires issuer + acquirer support | Requires issuer + acquirer support |
| Spend controls | Per-session limits, merchant allowlists | Delegated authority at card level | Delegated authority at token level |
| Status (2026) | Emerging, developer preview | Emerging, pilots | Emerging, pilots |
MCP vs A2A vs OpenAI Apps SDK
| MCP | A2A | Apps SDK (OpenAI) | |
|---|---|---|---|
| Direction | Agent ↔ tools/resources | Agent ↔ agent | Chat client ↔ app |
| Sponsor | Anthropic (open) | Google (open) | OpenAI |
| Use in commerce | Expose catalog/order ops as tools | Orchestrate multi-agent buying | Merchant app inside ChatGPT |
| Maturity | Emerging, growing ecosystem | Emerging | Emerging |
| Lock-in risk | Low (open protocol) | Low | Moderate (client-bound) |
Gaps in the stack
Where the Universal Commerce Protocol is most under-specified today:
- Policy interoperability across marketplaces. schema.org covers the open web; marketplaces each encode policies differently.
- Dynamic price and stock freshness contracts. No cross-actor convention for "how fresh is this".
- Agent attribution and commission. If an agent drives a sale, how is that recognized and remunerated?
- After-sales for agents. Returns, disputes and warranty claims initiated by agents on behalf of users.
- Trust signalling. Cross-platform merchant reputation that agents can verify.
- Taxonomy reconciliation. Google Product Category, GS1 GPC, Amazon Browse Nodes — still distinct.
These are the gaps we will follow most closely on this site.
Where to go next
- Return to the frame: What is the Universal Commerce Protocol.
- See how commerce interoperability is operationalized.
- Translate standards into action with the readiness checklist.