Skip to main content
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