# Agent

The `Agent` (represented by `BaseAgent` in code) is a public interface in ADK that serves as a blueprint defining identity, instructions, and tools for an agentic entity. It inherits from `BaseNode` and can be part of a larger workflow or act as a standalone agent.

## Key Characteristics
- **Name**: Unique identifier within the agent tree. Must be a valid Python identifier and cannot be "user".
- **Description**: Capability description used by the model for delegation.
- **Sub-agents**: Support for hierarchical agent structures.
- **Callbacks**: Supports `before_agent_callback` and `after_agent_callback` for intercepting lifecycle events.

## Entrance Methods

> [!IMPORTANT]
> Since agents now extend `BaseNode`, the original `run_async` entrance method is considered **deprecated**. Developers should rely on the new `run` method from `BaseNode` to execute agents as workflow nodes.

### `run` (Preferred Entrance)
The method inherited from `BaseNode` to execute the agent.

### `run_async` (Deprecated)
Legacy entry method to run an agent via text-based conversation.

**Arguments:**
- `parent_context`: `InvocationContext`, the invocation context of the parent agent.

**Yields:**
- `Event`: The events generated by the agent.

### `run_live`
Entry method to run an agent via video/audio-based conversation.

**Arguments:**
- `parent_context`: `InvocationContext`, the invocation context of the parent agent.

**Yields:**
- `Event`: The events generated by the agent.

### `from_config`
Class method to create an agent from a configuration object.