langchain/tools/file_management/write.py/WriteFileTool/_run
class WriteFileTool:    def _run(
        self,
        file_path: str,
        text: str,
        append: bool = False,
        run_manager: Optional[CallbackManagerForToolRun] = None,
    ) -> str:
        try:
            write_path = self.get_relative_path(file_path)
        except FileValidationError:
            return INVALID_PATH_TEMPLATE.format(arg_name="file_path", value=file_path)
        try:
            write_path.parent.mkdir(exist_ok=True, parents=False)
            mode = "a" if append else "w"
            with write_path.open(mode, encoding="utf-8") as f:
                f.write(text)
            return f"File written successfully to {file_path}."
        except Exception as e:
            return "Error: " + str(e)