A2A (Agent2Agent Protocol)
A2A (Agent2Agent Protocol) is an open specification for how independent AI agents -- built by different teams, on different frameworks -- discover each other's capabilities and collaborate on a task, instead of one agent needing custom, one-off integration code for every other agent it talks to. A server-side agent publishes an Agent Card, a metadata document describing its skills, service endpoint, and authentication requirements, which a client-side agent fetches to learn what the other agent can do before delegating work to it. Under the hood, A2A exchanges Tasks, Messages, and Artifacts over one of several interchangeable bindings -- JSON-RPC 2.0, gRPC, or HTTP+JSON -- so the choice of transport doesn't change the protocol's data model. Originally published by Google in 2025 and now maintained as an open, vendor-neutral specification, A2A solves a different problem than MCP: MCP connects one agent to the tools and data it uses, while A2A connects one agent to another agent it needs to delegate a task to.
By AdminKit team, Netbase JSC · Updated