When the heroes enter a combat and want to know information about their enemies (keywords, strengths, weaknesses etc) would the ability check require an action or is this a free action?
I have read Does D&D 5e have a rule for character knowledge about monsters? but it only discusses which skills to use, not what actions it would take.
My group thinks it should be a free action as you can ask your knowledge while you act. I think with 4 people in the group at least one always rolls high enough to get serious information. And of course it will happen at the start of every battle because it doesn't cost the PCs anything.
I am planning (if it's for free) to do either a group check or a passive check (like perception or insight, just with the appropriate skill), but I still think giving away information for free that can seriously change the outcome of the battle is quite cheap. Especially in Out of the Abyss, where you have many monsters with special features.
So - how does giving out monster information during combat work, action wise?