rasa-setting-up-a2a-agents

Connecting A2A External Sub Agents

External sub agents connected via the A2A protocol operate as autonomous entities that handle complex, multi-turn conversations independently. When invoked through a call step in a flow, the external agent takes control of the conversation until its task is complete.

This feature is in beta and available starting from Rasa 3.14.0.

Workflow

1. Ensure the external agent is running and exposes an A2A-compatible endpoint with an agent card.
2. Create the sub agent directory: sub_agents/<agent_name>/ with a config.yml (see "Directory structure").
3. Set agent.protocol: A2A and point configuration.agent_card to the agent card file or URL (see "Configuration").
4. Add authentication if the external agent requires it (see "Authentication").
5. Invoke the sub agent from a flow using an autonomous call step (see "Invoking from a flow").
6. Optionally customize input/output processing with a Python module (see "Customization").
7. Validate the project.

Directory structure

Each A2A sub agent lives in its own subdirectory under sub_agents/. Both rasa train and rasa run scan this directory by default; pass --sub-agents <path> to either command to use a different directory.

The agent name must be unique across all sub agents and all flow IDs.

your_project/
├── config.yml
├── domain/
├── data/flows/
└── sub_agents/
    └── car_shopping_agent/
        ├── config.yml              # required
        ├── agent_card.json         # local agent card (or use a URL instead)
        └── custom_agent.py         # optional customization module

Configuration

The config.yml requires agent.protocol: A2A and a configuration.agent_card pointing to either a local JSON file (relative to project root) or a remote URL.

# sub_agents/car_shopping_agent/config.yml

agent:
  name: car_shopping_agent
  protocol: A2A
  description: "Helps users shop for cars by connecting them with dealers"

configuration:
  agent_card: ./sub_agents/car_shopping_agent/agent_card.json