Identifying a Creature. The rules don't specifically address the situation where a player asks the GM if his or her character knows anything about the creature encountered. Knowing a creature's hit points, traits, abilities, and attack options is valuable in combat. Here is a house rule.
1. In some situations, the GM could simply rule that you know of the creature type in question, without requiring an ability check. The GM determines that you likely would have learned about or encountered a creature of this type before given your class level (experience), background, race, language fluency, or class.
2. In other situations, the GM could determine that you have a chance of knowing something about the creature type encountered, and require an ability check based on this creature type. Any proficiency bonus would apply as normal. The GM could grant you advantage because of your background, race, language fluency, or class.
3. Finally, in some situations the GM could determine that, given the creature's exotic nature or because it is so uncommon, you have no chance of knowing anything meaningful about it. No ability check would be permitted.