Agent2Agent (A2A) Protocol
A2A is an open protocol that lets independent AI agents built by different vendors or frameworks discover each other and exchange tasks, messages, and results over a standard wire format.
Description
Agent2Agent (A2A) is an open protocol specification originally developed by Google Cloud and donated to the Linux Foundation in 2025. Each A2A server publishes an Agent Card describing its identity, skills, and endpoint, and clients send messages to it that the server either answers directly or turns into an asynchronous Task with a defined lifecycle. The protocol defines transport bindings over JSON-RPC, gRPC, and HTTP/REST so agents can communicate across process and vendor boundaries without sharing an internal framework.
Solution
A2A is not an agent loop itself but a request/response and task-lifecycle protocol between agents: a client agent discovers a remote agent through its Agent Card, sends a message, and the remote agent returns a direct response or creates a long-running Task whose state the client polls or streams until completion.
Primary use cases
- cross-vendor agent interoperability
- runtime agent discovery via Agent Cards
- delegating tasks between enterprise agents
- multi-agent coordination across frameworks
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