no luck with parchment bags to cook meat/fish

I've tried 2 recipes using parchment cooking bags - they promised tender, juicy chicken breast. That did not happen lol. Tough and chewy, I guess overcooked. Baked in 350 oven for 25 minutes as per recipe. Then I baked cod. Recipe said to put green onions and chopped tomatoes on the bottom and layer cod over it, with olive oil and spices. Per recipe 400 degrees for 20 minutes. Vegetables were swimming in liquid (ick) and fish was undercooked in some places and overcooked in others. I must be doing something wrong? Cleanup is super simple, which is great, but I need better results. submitted by /u/OllieBear2023