When you train a seq2seq model on new summ or translation dataset or other seq2seq task and want to decide how many beams to use, should use length penalty or not, what should be the max seq length, what should be the no_repeat_ngram_size etc, all of these parameter affect the metrics , so this tool helps to make those decisions,
It does not use optuna, it just uses itetools.product to enumerate the different combinations and evaluate on them