What is AP2?

AP2 targets a specific gap in agent commerce: when an agent rather than a person clicking a buy button starts a payment, someone must be able to show that the user authorized it, that the request is genuine, and who is accountable. The project site presents AP2 as an open protocol for this purpose.

Its building blocks are mandates, which are signed records of what the user has allowed. The documentation describes a Checkout Mandate, covering the items and purchase details shared with the merchant, and a Payment Mandate, authorizing payment on a specific instrument and shared with parties such as the credential provider and payment processor. Each has an open stage, capturing constraints like a budget, and a closed stage, authorizing a finalized amount. Mandates are verifiable digital credentials, described as tamper-evident and cryptographically signed, and they are chained to form an audit trail for transactions with or without the human present.

The site calls AP2 an extension of the Agent2Agent protocol and also for MCP, and lists a sample that uses x402 for payments. The documentation is copyright Google under Apache 2.0, and mentions a donation to the FIDO Alliance with standardization work continuing in FIDO working groups.