langchain/callbacks/tracers/stdout.py/ConsoleCallbackHandler/_on_tool_start
class ConsoleCallbackHandler:    def _on_tool_start(self, run: Run) -> None:
        crumbs = self.get_breadcrumbs(run)
        print(
            f'{get_colored_text("[tool/start]", color="green")} '
            + get_bolded_text(f"[{crumbs}] Entering Tool run with input:\n")
            + f'"{run.inputs["input"].strip()}"'
        )