A2A Typical Flow Visualization

Agent-to-Agent Communication Flow

This diagram illustrates the typical interaction flow between a client and server in an A2A architecture.

sequenceDiagram participant Client participant Server Client->>Server: GET /.well-known/agent-card Server-->>Client: Agent Card Client->>Server: POST tasks/send or tasks/sendSubscribe Note right of Client: Includes initial message and Task ID alt Streaming Server-->>Client: SSE events (status updates, artifacts) else Non-Streaming Server-->>Client: Final Task object end opt Input Required Client->>Server: POST tasks/send or tasks/sendSubscribe Note right of Client: Same Task ID Server-->>Client: Continue processing end Server-->>Client: Terminal state (completed/failed/canceled)

Key Components

Discovery: Client fetches Agent Card from well-known URL
Initiation: Client sends initial message with unique Task ID

Processing Modes

Streaming: Server sends SSE events during processing
Non-Streaming: Server returns final Task object