Agent
Agent is a type alias for LlmAgent (Agent: TypeAlias = LlmAgent), the
model-backed agent most users instantiate. It is not the same thing as
BaseAgent, which is the abstract base every agent derives from.
BaseAgent extends BaseNode, so an agent is a node: it can stand alone under
a Runner or sit inside a Workflow graph.
Key fields
name— unique identifier within the agent tree. Validated: must be a valid Python identifier, and"user"is rejected because it is reserved for end-user input.description— capability description the model uses when choosing which sub-agent to delegate to.sub_agents— child agents. Names must be unique across the tree; each child'sparent_agentis wired up automatically.before_agent_callback/after_agent_callback— intercept the agent lifecycle.
Entrance methods
| Method | Use |
|---|---|
run_async(parent_context) |
Text conversation. Yields Events. Runs the before/after callbacks, the error callback, and invocation instrumentation around _run_async_impl. |
run_live(parent_context) |
Video/audio conversation. Marked @final — override _run_live_impl instead. |
run(ctx=..., node_input=...) |
Inherited from BaseNode, @final. This is what a Workflow calls when the agent is a graph node; it routes into _run_impl, which for BaseAgent delegates to run_async. |
Which one you call depends on the caller, not on age: a Workflow calls run(),
direct text callers use run_async(). Nothing in the source marks run_async
deprecated, and it remains the path every agent's real logic runs through.
Other methods
clone(...)— copy the agent, detached from its parent.find_agent(name)/find_sub_agent(name)— search the agent tree.root_agent— walk up to the top of the tree.from_config(config, config_abs_path)— build an agent from a config object. Both@deprecatedand@experimental; do not build on it.