[MENTION=20564]Blue[/MENTION]: In D&D 5e, one does not "use skills" on NPCs or PCs. They perform tasks.
There is an entire chapter in the PHB called "Using Ability Scores". I believe the terminology of "using" a ability check, or colloquially a skill check, is well understood and unassailable as a term to describe invoking them.
The outcomes of those tasks may be uncertain and carry with it a meaningful consequence of failure. If they do, then the DM calls for an ability check to resolve it. If the task does not have an uncertain outcome and/or a meaningful consequence of failure, the DM does not call for an ability check. These are not house rules.
Since a player determines how a character thinks and acts, the outcome of a task made to influence how the character thinks is not uncertain. Therefore, there is no ability check. These are also not house rules.
Thank you, this is a great communication - it shows me why you don't think there is a need for a check. I would like to put forth that there are uncertainties outside the DM telling the player what the character thinks or acts.
The case I want to bring up is that the check can be made to give the player information their character should observer by being part of the world. So that the player then has information on what their character knows
in-game and can decide what their character things or acts based on that.
Say the party is split and doesn't know where each other are. The party also knows there are ninjas hiding in the shadows who have attacked the party before.
Player A has their character hiding and sneaking along the edges of a courtyard.
DM switches to another player on the battlements above the dimly lit courtyard. Based on their passive perception, they could find out that there is someone in the courtyard. Or that there are two someone's in the courtyard (different stealth score). Or that one of them is their friend.
If the character saw no sneaking figures, they might continue on their way. If they saw one they might cast a single target spell on it. If they saw two they might case a area of effect spell. If they saw two but knew one was their friend they might go back to a single target spell. It's all up to the player.
Here we have one player needing to make a stealth check (it applies to the ninjas as well), and another getting a description of the world as there character would know it in order so that the player can then make decisions on what their character does.
I hope this shows that there's a case where the DM is providing information based on what the character experiences simply by existing in the world ("The DM describes the environment [PHB pg 6 'How to Play']), and not to dictate what the character is thinking or doing.