langchain/callbacks/manager.py/AsyncCallbackManagerForToolRun/on_tool_end
class AsyncCallbackManagerForToolRun:    async def on_tool_end(self, output: str, **kwargs: Any) -> None:
        """Run when tool ends running."""
        await _ahandle_event(
            self.handlers,
            "on_tool_end",
            "ignore_agent",
            output,
            run_id=self.run_id,
            parent_run_id=self.parent_run_id,
            **kwargs,
        )