Interactive · agentic commerce

The four protocols, and what each one actually gives a merchant

Filter by what you need, then hover any cell. The question is not which protocol wins — it is whether your platform has implemented any of them.

Protocol Discovery In-chat checkout Payment limits Vendor-neutral Where it runs
UCPUniversal Commerce Protocol ✓ ✓ ~ ~ AI Mode, Gemini
ACPAgentic Commerce Protocol ~ ✓ ~ ~ Assistant chat
AP2Agent Payments Protocol – – ✓ ~ Beneath checkout
MCP commerceModel Context Protocol ✓ ~ ~ ✓ Any capable agent
The row that decides the shortlist

Feed accuracy beats everything

Agents filter on values before they compare anything else. A missing attribute is treated as a failure, not a maybe — so stale stock and absent identifiers remove you before your copy is ever read.

Five minutes, every week

How to test whether you are visible

  1. 1Write five realistic shopper prompts, each with a budget and a deadline.
  2. 2Run them signed out, in two or three different assistants.
  3. 3Log who gets recommended, and the attribute you are missing.
  4. 4Fix the attribute, not the copy — usually it is a number nobody published.

Sources: Google Merchant Center and Google Developers on UCP; OpenAI on ACP; Mastercard Agent Pay and Visa Intelligent Commerce on programmatically enforced spending controls. Hover a mark for the detail. Nothing here is model-generated data.