[RPG] What can PCs find out about creatures using knowledge skills


I'm new to D&D and I'm a bit confused about using lore. I already saw Does D&D 5e have a rule for character knowledge about monsters? and know that a PC can use knowledge skills to learn about things, but I'm not sure what they can learn.

Let's say during or after a combat a player asks about the enemy creature, for example a goblin, and they want to use a knowledge skill for this. As the DM, I set a DC for the roll and if they succeed… what can I tell them about the enemy? Can I tell only goblin lore — origin, how they live, etc. — or can a DM even say its attributes such as AC, HP? Is there any way a player can even ask about enemies abilities or attributes? If an enemy monster has some special actions apart from melee/ranged attacks, is there any way for the players to find out by the rules when the DM must tell them?

Best Answer

You are the DM - it means whatever you want it mean.

Some people like to play the game with things like AC and hp a mystery and others prefer these things to be known to everyone. Both ways are 100% correct.

If you choose to play the first way then you are obliged as DM to make it clear in your description how strong the opponents are so the players' can make intelligent choices about when to engage and when to withdraw. Alternatively, if you put the numbers on the table then this is irrelevant.

Personally, I play with experienced gamers who have a pretty intimate knowledge of the rules and can usually pick from a brief description what they are up against. How do I reconcile the gap between what the player knows and what the character knows? Easy, if the player knows it the character knows it and vice-versa. How? Because the character grew up in a world with goblins and dragons so they know about goblins and dragons just like I grew up in a world with cars and Americans so I know about cars ( I don't understand Americans but that is due to general disinterest) :-)