What are agent payments? A2A and AP2 explained

Agent payments are when AI agents complete purchases and payments on the user's behalf — instead of you clicking through the checkout yourself. When an autonomous agent buys for you, a new problem appears: how does the store and the payment provider know the purchase really is what you asked for, and not the agent misunderstanding? The answer is a set of new protocols. Two of the most important are Agent2Agent (A2A) and Agent Payments Protocol (AP2).

A2A: how agents talk to each other

Agent2Agent (A2A) is an open standard for how AI agents communicate and collaborate across systems and vendors. It now sits under the Linux Foundation and passed over 150 supporting organizations — among them AWS, Cisco, Google, IBM, Microsoft, Salesforce, SAP and ServiceNow — in its first year, with SDKs for five languages. A2A lets an agent safely discover other agents and divide tasks between them, so a shopping agent can, for example, collaborate with a payment or logistics agent.

AP2: how the payment becomes trustworthy

AP2, announced by Google in September 2025 with over 60 partners such as PayPal, Mastercard, American Express, Adyen and Coinbase, tackles the trust problem head on. It uses mandates — tamper-proof, cryptographically signed contracts built on W3C Verifiable Credentials. A purchase is chained through three mandates:

• Intent Mandate — captures the user's high-level instruction ("find white running shoes under $100").
• Cart Mandate — the user approves a specific cart at a specific price.
• Payment Mandate — a derived credential the payment network sees.

Together the chain — from intent, to cart, to payment — creates a non-repudiable audit trail that answers who authorized what. This is what makes a store willing to let an agent pay.

How A2A and AP2 relate to MCP, UCP and ACP

These standards stack on top of each other, each with its own job. Model Context Protocol (MCP) connects an agent to tools and data. A2A lets agents talk to each other. AP2 makes the payment itself trustworthy. On top sit the commerce standards: UCP (Universal Commerce Protocol, Google-led) and ACP (Agentic Commerce Protocol, from OpenAI and Stripe, which powers Instant Checkout in ChatGPT). UCP explicitly interoperates with AP2, A2A and MCP — they are not competitors but layers in the same stack. Read more in the UCP explainer.

What it means for your brand

When agents both choose and pay, the sale is decided long before checkout — the moment the agent evaluates which products meet the user's intent. That means your product data has to be machine-readable and accurate, and your brand has to be visible and well-represented where the agent does its research. Want to see how AI portrays and recommends you today? Start with a review of your AI visibility.