langchain/callbacks/manager.py/CallbackManagerForChainRun/on_agent_action
class CallbackManagerForChainRun:    def on_agent_action(self, action: AgentAction, **kwargs: Any) -> Any:
        """Run when agent action is received."""
        _handle_event(
            self.handlers,
            "on_agent_action",
            "ignore_agent",
            action,
            run_id=self.run_id,
            parent_run_id=self.parent_run_id,
            **kwargs,
        )