Sell through AI assistants: checkout for ChatGPT, Gemini and others (UCP, ACP)

What an assistant needs

An assistant asked to “order more coffee beans, the same as last time” compares, picks, and then has to buy. To finish, it needs:

• Your products, with prices and stock, as data it can read rather than pages it has to guess from.
• A checkout made for agents, where it places the order and the person approves the payment, without typing card details into a form made for people.
• The steps after: change or cancel the order, see where it is, fetch the receipt, start a return.

Two open protocols describe a checkout for agents. UCP, the Universal Commerce Protocol, publishes a profile at /.well-known/ucp with the parts your shop supports: checkout, catalogue, orders and payment. ACP, the Agentic Commerce Protocol, publishes /.well-known/acp.json with a checkout and delegated payment. Some shop platforms publish one of them for you; others need an app or a plugin. Either counts.

How the payment itself works is in the payments guide.

A basket hand-off

If you can’t offer a checkout yet, you can still let an assistant fill a basket for a person to pay. Write a line in your llms.txt with a link template, for example:

- Basket hand-off (an agent fills the basket, a person pays): https://yourshop.example/cart/<variant_id>:<qty>

It counts as partly: the agent did the choosing, and a person still pays. On a site we can’t yet tell is a shop, a hand-off on its own can lower the score, because it brings the steps after an order into the count. Your details as data says how we tell a shop.

After the order: change, cancel, track, receipt, return

An order is the start of the job, not the end of it. Once an assistant can order from you, these count too, and a full score needs them:

• Change: update_order, modify_order, PATCH /orders/{id}.
• Cancel: cancel_order, DELETE /orders/{id}.
• Track: get_order_status, track_order, order_status, lookup_order, GET /orders/{id}/status, a UCP order capability, or an order lookup line in llms.txt, such as Order lookup API: POST https://yourshop.example/orders/lookup.
• Receipt: get_invoice, get_receipt, GET /invoices/{id}.
• Return or refund: request_return, start_return, request_refund, create_return, POST /returns, or a UCP return capability.

A lookup by order number and email address is a simple way to offer tracking and receipts. Returns services run portals made for people; ask yours for an API you can publish. For bookings, changing and cancelling are in the bookings guide.

What counts in the check

We read what your shop declares, and never place an order:

• Order: a UCP checkout, an ACP checkout, a Shopify storefront’s cart tools, or a tool or an operation such as create_order, create_checkout, purchase or POST /orders. Also an agent inbox that takes orders.
• Partly: a basket hand-off line in llms.txt or agents.md, or a cart-link tool such as create_basket_link: an agent fills the basket and a person pays.
• Catalogue: products with an Offer price and currency in your schema.org markup, a UCP catalogue, or tools such as list_products or search_catalog.
• Stock: check_stock or a UCP catalogue; availability on your offers counts as partly.
• The steps after, listed above.

Not counted: a checkout page made for people, a contact form, email or phone.