Until recently, an AI agent trying to buy something on a customer's behalf had no reliable way to do it — it had to scrape a page like a human would, guess at a checkout flow, and hope nothing changed between one visit and the next. That's changing fast, and it's changing because of a small set of open standards that are quickly becoming as foundational to agentic commerce as HTTP was to the web.
The three protocols worth knowing
| Standard | Who's behind it | What it does |
|---|---|---|
| MCP (Model Context Protocol) | Anthropic | An open standard for connecting AI agents to external systems and data — the first of its kind, and the foundation the others build conceptually on. |
| ACP (Agentic Commerce Protocol) | OpenAI & Stripe | A shared framework for retailer-agent interoperability, released under Apache 2.0 — lets an agent browse a catalog and complete checkout through a consistent interface. |
| UCP (Universal Commerce Protocol) | Announced at NRF with Walmart, Target, and Shopify already participating — aims at the same interoperability problem with major retail infrastructure behind it from day one. |
Why this matters beyond the acronyms
The practical effect of these standards is what the industry has started calling zero-click commerce: the gap between a shopper stating what they want and completing the purchase compresses into a single agent request. A buyer's agent states intent in plain language, calls the retailer's API, checks stock and eligibility, and either completes checkout or moves on — without a human clicking through a funnel built for browsers, not agents.
Payments have moved just as fast. Visa's Trusted Agent Protocol has gone from sandbox piloting with over a hundred partners to commercial availability. Mastercard already supports agent-initiated payments, and American Express has introduced purchase protection specifically for registered AI agent purchases. All three major U.S. card networks now support agent-initiated payments at scale — which removes what was, until recently, the biggest practical blocker to agentic checkout actually working end to end.
The B2B side is moving too: procurement agents are starting to negotiate directly with supplier sales agents — an inventory system detecting low stock and reordering automatically by having its agent transact with a supplier's agent, no person required in the loop. That agent-to-agent pattern needs more structured data and tighter API standardization than consumer-facing commerce does, and it's arguably the more transformative half of this shift.
What this means if you're evaluating agent-readiness
A retailer or platform doesn't need to pick a side between ACP and UCP today — both are early enough that the practical move is building on infrastructure flexible enough to speak whichever protocol a given agent shows up using, rather than betting the architecture on one winning outright. What matters more right now is the underlying discipline these standards all assume: a clean, structured, permission-aware API surface that an agent can query reliably, with the same accuracy a human would get browsing the site by hand.