In agentic checkout, an agent prepares a purchase against a specific merchant offer. The merchant calculates the valid cart, the customer approves the purchase or has delegated suitable authority, and the payment provider checks the payment. The merchant’s order confirmation is what tells the agent the order was created.
What happens during a purchase?
- Calculate the offer. The merchant confirms the variant, quantity, availability, total and delivery option.
- Get approval. The customer sees the valid total and confirms the order. With delegated authority, the system checks whether the order falls within the agreed limits.
- Complete payment and order creation. The payment provider returns its status. The merchant assigns an order number for the agent to show the customer. If a network error leaves the result unclear, the agent checks the existing status.
Where do protocols fit?
UCP and ACP describe interfaces between commerce platforms, assistants and merchants. The implementation of each channel determines which actions it supports. Separately, AP2 describes how mandates can prove delegated authority. Test the authority, payment and order status as distinct steps. A particularly useful case is a price change after approval. If the original approval no longer covers the total, the agent needs to present the updated offer.
Book chapters, articles and sources
- Chapter 7 · How protocols become a purchasing journey
- Chapter 8 · From the offer to the service that follows
- UCP, MCP and ACP compared: Choosing protocols for your shop
- Stefan Hamann · Agentic Commerce, Now Real: Shopware Launches ACP with a Live PayPal Prototype
- Google · Universal Commerce Protocol
- OpenAI · Agentic Commerce Protocol
- AP2 · Agent Authorization