Definition
The Agent Payments Protocol (AP2) is an open specification, announced by Google Cloud in September 2025, that defines how AI agents obtain and prove authorization to transact on a user's behalf. Its core primitive is the mandate: a tamper-proof, cryptographically signed statement describing what an agent may do. An intent mandate captures what the user asked for, and a cart mandate captures the specific purchase being authorized, producing an auditable chain from human instruction to completed transaction.
AP2 addresses the trust problem in agentic commerce. When an agent buys something, a merchant needs to know that a real user authorized this specific purchase, at this price, within these limits. Mandates make that verifiable after the fact, which matters for chargebacks, compliance, and dispute resolution in a way that a simple API call does not.
The protocol builds on Agent2Agent for messaging and capability discovery, with agents advertising AP2 support through their agent card. It is deliberately rail-agnostic: settlement can run over x402 stablecoin payments, card processors, or other providers that implement the settlement interface. This positions AP2 as the authorization layer of a stack whose other layers include the Agentic Commerce Protocol for in-chat checkout and MCP for tool and data access.
For brands, AP2 support is part of agent experience optimization. Being recommended by an AI assistant is the visibility problem; being transactable by one is the conversion problem. As agent-initiated purchasing grows, merchants that cannot accept an authorized agent payment will lose sales they already won at the recommendation stage.
Examples of Agent Payments Protocol (AP2)
- A user tells an assistant to reorder supplies under a set budget, and the agent carries a signed intent mandate that caps what it may spend.
- A merchant verifies a cart mandate before fulfilling an agent-placed order, confirming the exact items and price the user authorized.
- A finance team resolves a disputed agent purchase by inspecting the signed mandate chain rather than relying on server logs.
- A retailer implements AP2 for authorization and x402 for settlement so agents can complete purchases without a human checkout step.
