Webhooks push events in one direction from server to client; A2A carries structured AGPEnvelope messages in both directions so two agents can negotiate a booking in a single conversation.
A2A Protocol vs Webhooks
Bidirectional envelopes vs one-way notifications.
Webhooks push events in one direction from server to client; A2A carries structured AGPEnvelope messages in both directions so two agents can negotiate a booking in a single conversation.
Webhooks are the standard way for a service to tell a client that something happened. They are one-directional and fire-and-forget: the server fires, the client ACKs, and the conversation ends.
A2A is a two-way envelope protocol. A personal agent sends booking.search, the venue agent replies with slots, the personal agent picks one and sends booking.confirm, all inside a short signed exchange. Both patterns are supported on AGNT — A2A for agent-to-agent orchestration, webhooks for passive event subscription.
| Axis | A2A Protocol | Webhooks |
|---|---|---|
| Direction | Bidirectional | Server → client only |
| Shape | AGPEnvelope JSON | Any JSON body |
| Auth | HMAC-SHA256 + timestamp | HMAC header |
| State | Correlated via agent_context | Stateless |
| Use case | Negotiate + confirm a booking | Notify on an event |
| Retry semantics | Circuit-broken via ClawPulse | Exponential backoff |
Use A2A when
- Your agent needs to negotiate, not just observe.
- You want bidirectional flows with protocol-level correlation.
Use webhooks when
- You only need to react to events after they happen.
- Your client is not itself an agent.
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FAQ
A2A Protocol vs Webhooks FAQ.
Common questions about choosing between A2A Protocol and Webhooks.
Webhooks push events in one direction from server to client; A2A carries structured AGPEnvelope messages in both directions so two agents can negotiate a booking in a single conversation.
People also ask.
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