How to handle "I investigate for <this particular thing>" checks

Question

The characters enter a room, and get the general "what do you see" spiel. One player announces that he wants to "Investigate the room for ". (Let's say "investigate for odd books") or the rogue says he stops the group at the threshold and wants to "investigate the room for traps or other danger".

I can see 3 main options for how I proceed from here:

1. Treat everything after "I investigate ..." as flavour fluff, ignore it, and treat it as an entirely generic "Investigate the room" check.
2. Treat it as a very narrow investigation and only provide information that pertains to the specified target; the character can't notice anything that's not specifically related to the described investigation target, even if they, say, rolled a nat 20 and would otherwise have noticed the other suspicious things nearby.
3. Do something along the lines of treating this as a general check but with some hindrance on general targets and some benefit to the specific targets. (Say +3 on the investigation of the books, but -3 on the investigation of the room as a whole.)

#1. Seems to ignore the players role-playing and agency.

#2. Is going to end up with the players having to list out everything that could be interesting and doing tonnes of Investigation checks.

#3. Feels like the most interesting and flavour-ful way to handle it, and rewards the players for correctly guessing what's suspicious. But is also clearly the furthest deviation from RAW.

What's the normal way to handle this?

Answer 1

Ask "How do you do that?"

Players do things by describing their actions. "I want to investigate the room for odd books" is not an action, it's a desirable goal. An action would be:

• "I browse through every book on these shelves, until I find something like a spellbook"
• "I start tapping the walls, trying to find a hiding place"
• "I look under the bed. What do I see there?"
• "I glance at the table. Do I see any odd-looking books there?"
• ... other statement which gives insight about time, efforts and possible risks

Whilst describing a goal could be useful for determining the outcome, the general framework still states "players describe what they want to do", not "what they want to achieve". This is exactly how the rules describe the game process, see PHB page 6 "How To Play":

1. The DM describes the environment.
2. The players describe what they want to do.
3. The DM narrates the results of the adventurers' actions.

"I investigate" is a valid action too, although it is very broad and vague. Adding "for X" doesn't make it clearer, unfortunately. When in doubt, a DM is free to ask for clarifications from players.

Don't rush with dice rolls

When players say they want to "investigate", that doesn't automatically mean they have to make an Intelligence (Investigation) check, or any kind of ability check at all.

What you're talking about is probably the "I use X skill" mentality, which came from previous versions (3.x primarily). It assumes that a player states the exact skill she is using, then she states the goal she wants to achieve, then a dice roll is necessary using the mentioned skill modifier:

"I want to disable this trap using my Disable Device skill!" (rolls the dice)

This is not how 5e works anymore. 5e has no skill checks for a reason. Instead, players describe their actions, then the DM describes the outcome. A DM doesn't have to ask for a dice roll. PHB suggests to roll dice only "where the outcome action is uncertain", and the DMG goes even further:

One approach is to use dice as rarely as possible. Some DMs use them only during combat, and determine success or failure as they like in other situations. With this approach, the DM decides whether an action or a plan succeeds or fails based on how well the players make their case, how thorough or creative they are, or other factors.

More specific example

So, let's say the party searches for an ancient grimoire. The party enters a room, then a player states "I want to investigate for odd books". What happens next depends on the multitude of factors. What do they do, exactly? What can be found here? Is there any time limit? Are we talking about a deliberate hiding place, or is the room just untidy? And so on:

• If the room is a library, there're thousands of books here. "There are a lot of odd books here. How exactly are you going to find the proper one?" Maybe it's time to use the Locate Object spell, or ask NPCs, or do something else. Let your players be creative.
• If it's an empty cell, there are no books at all. You don't want to waste time on pointless dice rolls. "You see no books here, just cold stone walls and a crude trestle bed". Maybe players would investigate the bed — again, describe it without rolls and move on.
• A thorough search requires effort, but the party has plenty of time. On "How do you do that" they replied, "We leave no stone unturned until we find anything," so they will find all valuable things sooner or later, no dice roll is required. Just say what they did find. "You've spent a couple of hours and found an odd-looking spellbook and a sack of coins".
• If it's a living room with many things and time is the essence, the outcome is uncertain. "Okay, you want to search for books here. How do you do that? You probably have only a couple of minutes before the orcs arrive." Perhaps the player will say, "Okay, I want to rummage through shelves as quickly as possible." The risks and reward are clear, so you ask the player for a roll. The result is quite high but you know the book isn't there. "Well, you can't see any books here, but you've found an intriguing letter signed by Black Spider." Or, on a failed check: "In a rush, you accidently drop one of the shelves on the floor. Boom! You bet someone could hear this."
• Et cetera.

There can't be one "generic" answer, as there can't be a generic "Investigate the room" check in 5e.

Traps are a completely different topic

Speaking of traps, there is no silver bullet for them either. Moreover, making good traps is difficult, there are a lot of guides and videos on this topic. You can start with this one for example. Or watch this video.

Angry GM summarized the rolling part as "Only Roll When There is Chance of Success, A Chance of Failure, and A Risk or Cost of Failure" here (rule 2, hence Title Case). Being short and somewhat pithy helps me keep it in mind when GMing.

(kudos to @minnmass for the summary)

For instance, if you give players a chance to notice traps only when they explicitly say "I investigate the room for traps", they will probably say this in every room, and nobody will enjoy this. Instead, it might be a better option to use Passive Checks, or ask for a Wisdom (Perception) check right before the trap could spring.

Answer 2

tl;dr: I mostly use this sort of declaration to guide narration. Not all information is equally hide-able, and direct, mechanical benefits for generic, player-dictated rolls can be problematic.

Different information has differing flexibility for being hidden behind dice rolls

What I do varies a bit by situation, specifically what the player is looking for and what there is to find. My players tend to make "called" investigations like this in a few situations:

• They are looking for mechanical information (like traps, signs of enemy movement, etc. which will help them survive or conserve resources)
• They are looking for roleplaying-specific information (it matters for their character, but not for advancing or surviving the game)
• They are looking for plot-specific information (clues or events which move the game story forward)

Of these, I have found that it tends to be troublesome to withhold too much information on the latter two: plot information is necessary for the story to advance, and roleplaying information is usually important to players self-defining their fun in the game. Especially for plot information, it is undesirable for players to (unknowingly) define themselves out of finding it.

That sort of consideration really limits how much of a "penalty" you can apply to investigations of areas, however focused or unfocused.

There is, however, one thing I keep in mind for "called roll" situations: players do not get to dictate outcomes or successes when proposing actions. Saying "I check for traps" does not make a character any better at recognizing traps, understanding mechanisms, or anything like that. Try going outside and spending fifteen minutes digging random holes without any goal in particular. Then repeat but with a specific goal of looking for buried gold nuggets. I bet you'll find that wanting to find gold really doesn't change anything about the process, nor does it change how much gold you find.

The only exception to this that I've found meaningful is when there is limited opportunity to search, commonly a time limit or some scarce resource used in the searching.

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Degrees of success

I frequently use the "degrees of success or failure" model of interpreting dice rolls in D&D 5e, and it seems especially useful for players that try to powergame (for lack of a better word) like this. Since a disguised trap could look like basically anything (or nothing!), even a search for traps, specifically, a trap-searcher will still need to make a pretty expansive investigation.

Degrees of success make it possible to convey information incompletely, which is very useful for a situation like the one described in the question. A floor tile might look out of place, but not be part of a trap. Or it might be part of a trap, but the specifics of what that trap is are unclear.

If a character is so focused on traps that they barely notice other points of interest, those others might get brief and intriguing mentions but no more details. I like having the flexibility to make sure that vital information is conveyed, but not necessarily highlighted or fully explained in the moment. Particularly if the PC's attention is fixed elsewhere.

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Player declarations of what they are thinking about are important for narration

A player that wants to look for traps is concerned about traps! Whether or not I would consider giving some sort of bonus or penalty to their examinations, the narration is more trap-themed: I emphasize dangerous looking pieces of the environment and the uncertainty surrounding the entire situation:

The bas relief carvings on the wall seem like they have a lot of sharply cut stone details-- they're definitely sharp enough to cut flesh. The uneven stones paving the floor make each step seem ominous, and they somehow all seem out of place! The damaged ceiling above the far door looks almost like it could come down at any moment.

If someone wants to find indications of traps, lots of things might look trap-related enough to capture their attention. Unless it's an excellent roll, I find it best to not give definitive, binary information (that is a trap, and it looks like it will drop a swinging blade!). Players can still learn enough to be cautious, and their investigation is still helpful in making the situation safer than it might otherwise be.

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Ad-hoc modifiers can be tough to work with

While I do sometimes fiddle with roll details in the course of the game I resist doing it in this kind of situation. It can be difficult to know in advance how much an arbitrary +/-3 will shift the distribution of roll outcomes, and you might end up virtually guaranteeing success or failure without meaning to. When I do want to adjust this sort of thing I generally adjust the DC of the check. It's easier (for me) to remember how tough a DC 10 is vs. a DC 15, keeps the math easier (and therefore faster and less error-prone), and is still invisible to players.

It is also tricky to allow players to unilaterally declare such a modifier, especially just because they asked for it. "I look for traps" giving a +3 for trap detection is only a short hop away from "I try to land a hit" in combat giving an arbitrary bonus to an Attack roll.

If you really want to let players get a benefit out of focusing their attention in this way, and especially if you want there to be a corresponding impediment (+3 for traps, -3 for anything else, for example) I'll recommend 5e's Advantage and Disadvantage mechanic. You could, for example, call for a roll of 2d20, taking the higher roll for their focus and the lower for anything outside of their focus.

I've never used that two-rolls-in-one mechanic, but I've definitely used the "roll 2d20" without explaining why. My players have been excited to know that there is something unusual going on, but not knowing what it is, or even if it is to their benefit or not.

Answer 3

It depends on the situation

In general, I prefer that the players are specific about what they're doing, but I'll help them by using their specific words as a guideline, not a hard limitation. I typically allow a check to find things that weren't explicitly searched for, as long as it makes sense that the act of searching for X could reasonably uncover Y.

For example, if somebody is going to rifle through a desk looking for a signet ring, they could reasonably stumble across anything concealed in the desk, but not the concealed door behind the tapestry.

Similarly, if the rogue stops everyone and says he'll check for traps, then that's what he's doing -- he's not searching for clues or signet rings or valuable books. But I might well allow that roll to cover finding other hidden features of the room, like a secret door or a safe behind a painting, because it's sensible that in searching for traps he might locate things that initially appeared to be potential traps, but weren't.

I don't want to train my players that they should be vague about their actions lest I hold them to their exact words. I would much rather have players who declare actions like "Johann is going over the bookshelves to see if there's anything that looks rare, valuable, or magical" rather than a dull "I search the room", and I don't want to punish them for being specific.

Going the other way, if somebody says "I search the room", then my response depends on what I have going on there. If it's just a piece of setting with nothing much to find, I'm really not even going to call for a roll; I'll just tell them there's nothing more than what I've already described. If it's a small room but there are things to find, then I'll just have them roll for it. But if it's a large, complicated room with lots of stuff in it and things to find, then I'm going to ask for a more specific action than just generally searching "the room".

Answer 4

description and intention

You generally want to things from your players, description and intention. What they are doing and why they are doing it.

I had a player describing in detail how he searched a floor in dungeon. I though they were searching for traps so told them you find nothing out of place. They were really searching for footprints, which I had not even considered. Had I known what they were doing they would have found signs of activity telling them the dungeon was occupied. In the same way "I search for traps" only gives you half the information, "kneel down and closely examine the floor" can also cause problems.

Ideally you want "I kneel down and closely examine the floor for traps." Description and intention. Intention tells you want the players want, description tells you what information you should give them, including extra information they may not specifically be looking for. You don't want to punish players for being specific, you want to reward it.

Lets say your players say "I go through all drawers in the desk and flip over the bed, Specifically trying to find books or records"

now lets say there is a book but it is too well hidden and their roll fails. You can say "as you search through the desk and bed you don't find any books or records but you do find a sack of silver coins. You also find ink, pens, and a blotter used for writing but oddly nothing to write on."

This may suggest there should be records but they are either hidden or have been removed. Had they not mentioned searching for records I might not have mentioned the ink and pen, but because they stated a goal I gave them more information connected to their goal. This rewards players for stating a goal as well as an action, otherwise you could give misleading information. Just because a player states a goal does not mean they cannot find other things, but it does tell you what the player is thinking, which is is very useful information.

Now lets alternative say there is no book, you can say, "you don not find records nor do you see anything that indicates writing or record keeping. You do however find a sack of silver coins."

Again I am giving more information based on their stated goal, there is no evidence of records or books in this location, while also giving them the stuff they would find but the stated actions.