---
title: "How an agent checkout flows, per protocol | Agent Ready Checkout"
description: "How an agent checkout actually flows, per protocol: In every live flow the agent never becomes the seller. Every claim has a source and a read date."
canonical: https://agentreadycheckout.com/guides/how-an-agent-checkout-flows
site: "Agent Ready Checkout"
last_updated: 2026-11-04
date: 2026-11-04
section: "Guides"
---

# How an agent checkout flows, per protocol | Agent Ready Checkout

> How an agent checkout actually flows, per protocol: In every live flow the agent never becomes the seller. Every claim has a source and a read date.

Source: https://agentreadycheckout.com/guides/how-an-agent-checkout-flows
Site: Agent Ready Checkout
Last reviewed: 2026-11-04

Guide

# How an agent checkout actually flows, per protocol

In short

In every live flow the agent never becomes the seller: it discovers the product, builds a cart or session, obtains a scoped token or one-time card after the user approves, and hands it to the merchant, who charges through its own processor.

## What the sources say

-   UCP: the business publishes a profile at /.well-known/ucp; the platform sends its own profile URI in the UCP-Agent header; capabilities are negotiated and a payment handler is chosen from the payment\_handlers registry. [ucp.dev](https://ucp.dev/latest/specification/overview/), read 4 Nov 2026.
-   Google UCP checkout: the shopper pays with details saved in Google Wallet; Google passes standard card numbers (FPANs) and the merchant charges through its PSP. [support.google.com](https://support.google.com/merchants/answer/16837055), read 4 Nov 2026.
-   ACP: the merchant hosts checkout session endpoints the agent creates, updates and completes; the payment arrives as a delegated token such as a Stripe Shared Payment Token. [github.com](https://github.com/agentic-commerce-protocol/agentic-commerce-protocol), read 4 Nov 2026.
-   A Stripe Shared Payment Token is a scoped grant to the seller with a currency, maximum amount and expiry. [docs.stripe.com](https://docs.stripe.com/agentic-commerce/concepts/shared-payment-tokens.md?agent-seller=seller), read 4 Nov 2026.
-   Link Agent Wallet: the agent creates a spend request, the user approves, and Link returns a one-time-use payment credential. [docs.stripe.com](https://docs.stripe.com/agentic-commerce/agents/link-agent-wallet), read 4 Nov 2026.
-   x402 and MPP: the server answers HTTP 402 with payment requirements, the client pays and retries; MPP returns a Payment-Receipt header. [mpp.dev](https://mpp.dev/), read 4 Nov 2026.
-   AP2: the agent collects a Checkout Mandate and a Payment Mandate as signed credentials before payment, for human-present or human-not-present purchases. [ap2-protocol.org](https://ap2-protocol.org/), read 4 Nov 2026.

## Profiles named in this guide

-   [Agentic Commerce Protocol (ACP)](https://agentreadycheckout.com/protocols/acp)
-   [Universal Commerce Protocol (UCP)](https://agentreadycheckout.com/protocols/ucp)
-   [Agent Payments Protocol (AP2)](https://agentreadycheckout.com/protocols/ap2)
-   [x402](https://agentreadycheckout.com/protocols/x402)
-   [Machine Payments Protocol (MPP)](https://agentreadycheckout.com/protocols/mpp)
-   [Stripe](https://agentreadycheckout.com/processors/stripe)

## Read next

-   [Who is merchant of record in each protocol](https://agentreadycheckout.com/guides/who-is-merchant-of-record)
-   [How to support UCP on Shopify](https://agentreadycheckout.com/guides/support-ucp-on-shopify)
-   [The protocol support matrix](https://agentreadycheckout.com/matrix)

## Sources

1.  [UCP specification overview](https://ucp.dev/latest/specification/overview/), read 4 Nov 2026
2.  [Merchant Center help: UCP-powered checkout](https://support.google.com/merchants/answer/16837055), read 4 Nov 2026
3.  [ACP repository README](https://github.com/agentic-commerce-protocol/agentic-commerce-protocol), read 4 Nov 2026
4.  [docs.stripe.com/agentic-commerce/concepts/shared-payment-tokens.md](https://docs.stripe.com/agentic-commerce/concepts/shared-payment-tokens.md?agent-seller=seller), read 4 Nov 2026
5.  [Stripe Link Agent Wallet docs](https://docs.stripe.com/agentic-commerce/agents/link-agent-wallet), read 4 Nov 2026
6.  [Machine Payments Protocol](https://mpp.dev/), read 4 Nov 2026
7.  [AP2 protocol site](https://ap2-protocol.org/), read 4 Nov 2026

Last reviewed 4 Nov 2026

## Edition

Matrix edition of 4 Nov 2026.

Reviewed 4 Nov 2026, [7 sources](#sources-h).

## Method

[How cells, sources and read dates are defined](https://agentreadycheckout.com/method)