Faolyn
(she/her)
IMO, that's actually bad. It limits your options for describing characters when you say things like "they're fidgeting, which is indicative of lying." Not only is that not true in real life (meaning many people wouldn't think to connect it without you telling them that), but it means that we can't trust you, the DM, to have a character who fidgets who isn't a liar. Furthermore, it makes all your characters stereotypes. "Whoops, he just fidgeted, guess he's a liar." Or worse: "Looks like this guy's a liar; why not just kill him now and get it over with?" It honestly doesn't matter if you say that fidgeting "may" indicate the person is a liar. You're either saying the character is a liar, or you're setting us up to not believe this person when they're telling the truth.Insight is specific in what is being examined in the action the PC is taking. I think it's best to cleave as closely to that as possible. Not that I would necessarily describe the body language, speech habits, or mannerisms the same every time as is implied by your assertion, as for fidgeting in other NPCs indicating they may be lying - good! That means the player is paying attention, retaining information, and then applying what they learned in the game. That's a good result and an example of player (and perhaps character) skill. However, it's still an assumption on the part of the player and taking action to verify one's assumptions is smart play.
Secondly, if you say "fidgeting is indicative of lying," well, that's kind of offensive to any player who fidgets. If you had said "you noticed that he fidgets when he lies," that's different, because that's an individual tell. So you should probably watch how you describe these things.
Thirdly, it's really pretty mean to test player skill in remembering a given tell. I have ADHD and a terrible memory. Unless you blow fidgeting up to ridiculous levels, I might not remember even that detail half an hour later. Why punish my character because I have problems?
And as I showed, no, you're not.As well, let's keep this in context. You have a particular way you want players to portray their character in order for you to think of them as roleplaying correctly. That is a bias that may show up in how you narrate the results of the adventurers' actions. As you can see, I'm careful to avoid this.
And yes, I do want players to stay in character. Is there a reason why their character is never intimidated by anyone? Is it in your background? Or is it just something you pull out whenever you feel like no matter how appropriate to the setting, your character, or the NPC in question?