langchain/tools/spark_sql/tool.py/ListSparkSQLTool/_run
class ListSparkSQLTool:    def _run(
        self,
        tool_input: str = "",
        run_manager: Optional[CallbackManagerForToolRun] = None,
    ) -> str:
        """Get the schema for a specific table."""
        return ", ".join(self.db.get_usable_table_names())