By RAW: Does a creature know that it is hidden?

Question

When a creature attempts to Hide it makes a Stealth check, which is compared to the passive Perception of opposing creatures that may notice it, or a group check if there is more than one.

1. Does the creature attempting to Hide know whether or not is has successfully hidden?

2. If an opposing creature decides to take the Search action, making a Perception check to attempt to detect the hiding creature, does the hiding creature know if they have remained hidden?

3. Does the hiding creature know that the Search action has been taken?

This question is NOT about whether or not a player knows the result of their own roll. I did not ask if ingame characters know about gameplay mechanics or about the rolls of dice at all. It is about whether or not they know the result of checks, and whether they would reasonably be able to infer actions of other creatures.

Answer 1

Knowledge is often up to the DM to provide

The PHB (page 6) covers how actions are generally handled(emphasis mine):

1. The DM describes the environment. The DM tells the players where their adventurers are and what's around them…

2. The players describe what they want to do. […] the DM listens to every player and decides how to resolve those actions.

3. The DM narrates the results of the adventurers' actions.

In the case in question, we have a character who has said that they want to Hide to become unnoticed and explains how/where they will do so. The DM needs to decide if it's reasonable and if a roll is required (yes, it's so easy to hide, you're hidden - no, there is no way for you to hide, there is no attempt to be made.) The player makes the requested roll (most likely Stealth, but again this is up to the DM), and then the DM narrates the result.

It's really about the narration

So now you've got a situation where the DM has called for a roll and the player has made one. It's now up to the DM to describe what happens. If it's a 'failed' roll, maybe they describe noise being made, or some other environmental stimulus being triggered. Or that the player notices another creature noticing them. They can also choose to do none of the above and tell the player they believe they're hidden. It's all up to the DM and the table responding to the DM to determine what works best and is fun for everyone.

So in the case of a stealth attempt we are have an event where a player wants to hide. This is the action, the results of that action can be numerous and all are available as results (including being found or not being found.) This is in someways a Schroedinger's cat. WHen you declare your attempted action, it contains all possible results. Once the player rolls, the DM and the table see the result and the DM determines and narrates the result as they see fit. Some tables may like knowing, others may prefer not to. Both are perfectly acceptable as well as any option in between.

Answer 2

This is a matter of playstyle

The extent to which ludomechanical constructs-- such as ability scores, spell levels, hit points, and class levels-- are a part of the fiction is a matter of playstyle.

• Some groups will have characters say things like, "Aw man, 12d6 damage from the fireball? That's a 7th level spell slot. We better watch out for teleport; he probably knows that spell if he's got slots that high."
• Some groups will have characters say, "Alack and alarum! The flames of this evil magus art so hot methinks he wields power great enough to rend the very fabric of this world in twain-- we ought to expect that he shall endeavor to do so and beat a cowardly retreat if we his plans set awry."
• Some groups will have players make their characters act like they don't and shouldn't know that an enemy with a pointy hat and robes and a staff not wearing any armor is more likely to cast spells than a hulking dude in full plate with a tower shield in one hand and a waraxe in the other.
• Some groups won't even let players know how much damage they've taken or how much hp they have left.

The rules favor to a moderate extent the frame that the players should be allowed to know everything their character's know and vice versa-- that's the position from with combat options are generally balanced, for example. But the game remains playable, if very different, when this paradigm is shifted one way or the other.

How does this apply to hiding?

Well, first of all, even if a player knows whether or not their PC is hidden-- or a DM knows whether or not a given NPC is hidden-- that doesn't necessarily mean that the creature knows that. We can't jump from definitely allowed out-of-character knowledge to definitely allowed in-character knowledge like that; that's not a valid inference. Instead, if we lack any explicit guidance as to in-character knowledge, we have to turn to our group's method of handling that sort of information. We do, in fact, lack that sort of explicit guidance with the stealth mechanics, including the 'hide' action, so this is, obviously, necessary.

However, there's more: the rules also do not say whether or not players know when their character is hidden. While ordinarily this would mean that players don't know that information-- you normally don't get to do stuff unless the rules say you can-- the rules very much assume that players do know that information: for example, players are expected to roll their attack rolls and if they have incomplete information about conditions potentially granting advantage or disadvantage, that doesn't work practically-- you have to tell them at least some of the times or roll for them at least some of the times and doing any of that part-way is very much outside the rules. Page 5 of the DMG does implicitly suggest it's normal for the DM to roll damage rolls the PCs make instead of having them do so, though that contradicts much of the PHB and the player-facing parts of the DMG (5e's rules aren't intended to be consistent or coherent as a whole), but nothing is said at any point about DMs making attack rolls for player characters.

The rules also do not say whether or not a DM knows if their NPCs are hidden-- that may seem inherent in their running of the game, but one could imagine an esoteric but RAW-compliant system wherein only the person controlling the being being hidden from knows whether the attempt was successful or not. Again, the rules very much seem to expect, even though there is no explicit text, that the DM should know what's going on-- for example the rules declare the DM to have responsibility for refereeing the rules.

So, then, the rules do not tell us whether or not a creature's controller knows when it has hidden successfully some, all, or none of the time, nor, having answered that question affirmatively, whether the creature itself knows that. No mechanism is provided for resolving this absence of rules except for the advice on page 34 of the DMG; the section titled "Play Style".

Answer 3

This is not covered by the rules intentionally

Your question is very logical, and I guess it naturally comes from the following points:

1. The game rules define the game world
2. According to these rules, a creature can take the Hide action
3. After taking the Hide action, a creature can be or not be hidden

But does the creature know the outcome of its Hide action? It is a missing piece in the rules, so you've asked about it. Plain and simple, right? Why can this cause any misunderstanding and arguing?

Well, that's because the premises up above are not correct (or they are table dependent, strictly speaking). They suit the 3.5e or Pathfinder quite well, and are definitely true for a computer game, but they work poorly in the 5e paradigm. The Fifth edition tries to simplify rules and in the same time it moves to the older (2e AD&D-ish) paradigm, where the narrative truth was put ahead. You can read more about this paradigm in the A Quick Primer for Old School Gaming essay by Matthew Finch.

The rules do not define the game world

In the world a breastplate protects you because it is hard and sturdy, and it covers your vital organs. We, the players, use this simplified one-number abstraction only when we resolve a so-called "attack roll", in order to do it more easily. That does not mean the breastplate have have its "AC 14" somewhere.

The rules are not like the laws of physics applying to the game world. The rules is a DM's tool, which they can use to figure out an outcome of a situation. For more information, read "The Role of the Dice" chapter in the DMG. My point is — all the things you can read in the Player's Handbook do not encompass the whole game world. So in the game world creatures can (and will) hide because that's how they live, not because there is "the Hide action" in the PHB.

PHB gives you basic roleplaying guidelines and basic game mechanics, so you know what to expect from the DM. But it does not tell you what a DM should do, nor it describes any actual "laws" of the world. Instead, the game world is supposed to be vast and living, and you explore it, working with your DM through a conversation. For More information read PHB page 6 "How to play" and DMG page 9 "A World of Your Own".

You don't "take the Hide action" in order to hide

Well, that's a tricky one, so let's talk more about D&D history a bit. There is a reason why skill checks were removed in 5th edition.

In previous edition, players are supposed to say "I use X skill" when they wanted to achieve some goal. So you declared the mechanics and get the effect. Now you describe what do your character do in the first place, and then the DM might (or might not) use any game mechanics in order to resolve the outcome.

So you don't hide because you've taken the Hide action. The flow was reversed — now you take the Hide action because you're hiding, and you're hiding because, as a player (or a DM), you are describing the respective character actions. Things are more strict in combat though, but in general, "rules as written" does not mean "the only right thing" anymore — DMs are supposed to stick to the narrative truth, going with what's best for their story, not just "following the rules as strict as possible". That's why the rules are intentionally silent on many corner cases now.

"Hide" action in the rules does not actually describe hiding

The Hide action is a part of the "actions in combat" chapter. That does not mean you can not hide out of the combat. That means these particular mechanics matter in combat because of the action economy, so the action economy is the thing the rules description says about:

1. Hiding in combat should have benefits for attack in terms of mechanics; that's why you have Advantage
2. Hiding in combat is powerful because of the positioning, so it spends resources (it takes an action, unless you have a feature that allows you to use a bonus action)
3. Hiding in combat is also risky, so it's not automatic; that's why it requires us to roll dice

But these particular mechanics do not describe all the benefits from hiding. The rules intentionally do not say things like "enemy is (not) aware of you when you are hiding" because it's not a matter of mechanics now, it's a matter of the common sense, a current context and your narrative positioning (more on this later).

A creature is not either "hidden" or "not hidden"

"Hidden" is not a condition nor a boon a creature can have. Instead, "hidden" describes your narrative positioning. You can't be just "unseen and unheard", you are always unseen (or unheard) by somebody.

But your whole positioning means even more. Imagine you're a rogue searching through a manor, suddenly you hear a guard coming through the corridor. What do you do?

1. You freeze, staying still, making no noise, waiting for the guard to leave
2. You stand right behind the door, ready to stun an enemy with your sap
3. That nearby chest is empty, you get into that chest and close it, leaving a small slit to peek out

All three situations can be modeled with the same "Hide action" so they are identically in terms of mechanics, but they differ drastically in terms of the narrative positioning. It's a thing in 5e now, a good DM should take it into the consideration.

If rule do not cover this, how to understand, what's going on

So what do you do? You use the common sense. In the real world, do you know if you're not longer hidden? When someone notice you, no "eye" icon appears in front of you, neither you hear an alarm sound. Instead, you can (or can not) figure it out by the behavior of the creature searching for you. The same approach can be used in the 5e game.

Answer 4

Begin and End with the Fiction

Consider Ken the kobold, who is attempting to hide from some adventurers.

If the adventurers yell, "There's a kobold over there!" and shoot bows at him then he certainly knows he failed to hide. If they ignore him then he knows that either he sucessfully evaded their notice or they are bluffing.

If he sees the adventurers carefully looking around and shushing each other in order to listen, that's a clear indication that they are spending time and effort searching.

Answer 5

Characters do not know metagame information. Stuff that happens at the table - dice rolls, modifiers, out of character chat, etc. - is unknown to the characters. Any arguments based upon that metagame knowledge (i.e. rolling with Advantage, off-hand comments by the DM, etc.) are invalidated by that simple fact.

As in real life, the characters know what they are attempting to do and what appears to be happening.

If a character is attempting to hide then that character knows stealth is being attempted. If others react to the character, indicating that the character is not hidden, then the character knows that. If others spot the character but do not react to the "hidden" character then that character may believe she is Hidden when she is not; Wisdom (Insight) can be useful here.

At no point do the rules indicate a large alertness mark appears over observers. Nor do the rules indicate that characters possess a kind of Elder Scrolls "eye" to indicate stealth. The only way characters know they are Hidden if if the world reacts like they are hidden. And that reaction may be a lie.

Answer 6

If the one making the search action does something to let the player know they have been found then yes. Shouting at them, shooting at them, etc. Otherwise no, the player continues on as if they are hidden and the DM let's them know if they succeeded or not when they act (Whether or not they get Advantage on their attack during combat being a prime example.)