A2A Server

Enable Agent-to-Agent (A2A) communication for agent collaboration.

What is A2A?

A2A is a protocol for agents to discover and communicate with each other across different systems.

Enabling A2A

export AK_A2A__ENABLED=true
export AK_A2A__URL=https://your-domain.com/a2a
export AK_A2A__AGENTS="*"            # or a comma-separated list of agent names
export AK_A2A__TASK_STORE_TYPE=in_memory  # 'in_memory' or 'redis'

or

a2a:
  enabled: true
  url: https://your-domain.com/a2a
  agents:
    - "*"          # expose all agents (or list specific agent names)
  task_store_type: in_memory

The A2A routes are mounted on the main REST API server under /a2a; use api.port (or AK_API__PORT) to change the port.

Starting A2A Server

from agentkernel.api import RESTAPI

if __name__ == "__main__":
    RESTAPI.run()

Agent Capabilities

Each exposed agent automatically publishes an A2A agent card (via the framework adapter's get_a2a_card()), describing its name, description, and endpoint.

Agent Discovery

List all exposed agent cards:

GET /a2a/catalog

Each agent also serves its own well-known card:

GET /a2a/{agent}/.well-known/agent-card.json

Agent Communication

Each agent is mounted under /a2a/{agent} with the standard A2A protocol routes (provided by the A2A SDK's REST adapter):

Route	Purpose
POST /a2a/{agent}/v1/message:send	Send a message to the agent
POST /a2a/{agent}/v1/message:stream	Send a message with streamed protocol responses
GET /a2a/{agent}/v1/tasks	List tasks
GET /a2a/{agent}/v1/tasks/{id}	Get a task
POST /a2a/{agent}/v1/tasks/{id}:cancel	Cancel a task
GET /a2a/{agent}/v1/tasks/{id}:subscribe	Subscribe to task updates
GET /a2a/{agent}/v1/card	Get the agent card

Incoming A2A messages are executed through the same AgentService pipeline as REST requests: hooks, guardrails, and session persistence all apply.

Multi-Agent Network