Glossary
Agent-to-Agent Protocol (A2A)
Agent-to-Agent (A2A) is the open protocol for one AI agent to communicate with another — a buyer's agent negotiating with a merchant's agent. Agents publish an Agent Card at /.well-known/agent.json declaring their capabilities and how to reach them.
A2A is under Linux Foundation governance and uses JSON-RPC over HTTPS. It's protocol-agnostic about what the agents discuss — UCP supplies the commerce vocabulary on top of it. For most merchants this is a later-stage concern than getting their product data and checkout legible.