The Agent-to-Agent (A2A) Protocol enables standardized communication between AI agents, allowing them to discover each other’s capabilities and collaborate on complex tasks.
What is A2A?
The A2A Protocol is a JSON-RPC based specification that defines:
- Standard Communication: JSON-RPC messaging with streaming and non-streaming support
- Agent Discovery: Automatic agent cards describing capabilities and endpoints
- Rich Interactions: Tasks, status updates, and artifact sharing
- Interoperability: Works across different frameworks and platforms
Quick Start
Every agent served with Agentor automatically supports A2A:
Your agent is now discoverable at:
Agent Card
The agent card is a manifest that describes your agent’s capabilities:
The agent card is automatically generated from your agent configuration.
A2A Endpoints
When you serve an agent, these endpoints are automatically created:
GET /.well-known/agent-card.json - Agent discovery
POST / - JSON-RPC endpoint for all A2A operations
POST /chat - Simplified chat endpoint
Supported Methods
message/send - Send a message and get a response
message/stream - Send a message and stream the response
tasks/get - Get task status (if implemented)
tasks/cancel - Cancel a running task (if implemented)
Custom A2A Server
For advanced use cases, customize the A2A controller:
Streaming Responses
The A2A protocol supports Server-Sent Events (SSE) for streaming:
Server Side
Client Side
Send a streaming request:
Task Management
A2A includes task lifecycle management:
Multi-Agent Orchestration
Coordinate multiple agents:
Agent Discovery
Discover available agents by fetching their agent cards:
Best Practices
Deployment
Deploy A2A-enabled agents to Celesto:
Your agent will be available at:
Next Steps
Last modified on May 5, 2026