Why it matters

Multi-agent systems are the future of complex AI applications. Without a standard protocol, every integration is bespoke. A2A aims to fix this the way HTTP standardized web communication.

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The architecture

Roles: Client (initiator) and Server (invoked agent). Both are agents; roles apply per interaction.

Discovery: agents advertise capabilities via well-known JSON documents.

A2A core rolesClient agentsends taskServer agentprocessesCapabilities docadvertises skillsTask lifecycle: submit → work → stream updates → complete; standard message types across all
A2A protocol roles.
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How it works end to end

Message types: standard shapes for task submission, status updates, results, cancellation, error.

Auth: OAuth, API keys, mTLS — flexible per deployment.

Streaming: agents can stream progress updates back to client.