Something else I'd point out. Mother May I and "Yes And" are not the same at all. I'd argue they are, in fact, polar opposites. In a Mother May I situation, the DM determines that only a certain phrase (or set of phrases) will resolve the challenge. Unless the player specifically states this phrase(s) the player cannot succeed at this challenge. In a Yes And situation, the player can state any solution (presuming that it is made in good faith) and the DM is beholden to accept that solution as true. It's the complete opposite of Mother May I.
Now,
@Snarf Zagyg, I will freely admit my ignorance of Free Kriegspiel and related games. It's not anything I've ever looked into. So, as a question, do they base resolution on "Yes and"? So long as the player makes a reasonable (for a given value of reasonable) attempt to resolve the challenge, is the DM beholden to accept that resolution?
Because, the thing is, I do see Mother May I style resolution as poor gaming. It's very poor design because it leads to frustration among the players and teaches players to not rely on the DM to the absolute extent possible. It's inherently antagonistic between the person running the game and the players because it forces the players to play to the GM and not the game. It's also inherently meta-gaming because, again, I don't have to interact with the game world, I have to guess what the GM intends using the clues provided by the GM. It places the GM front and center of all challenges, rather than placing the challenges front and center.
If your players (not you
@Snarf Zagyg, I'm addressing anyone reading this) immediately look to their character sheets every time you propose a challenge, be it combat, social or exploration, that's because the players have been taught, either by you or by another DM they've had in the past, that the only way they can reliably interact with the game world is through whatever is written on their character sheet. That's why I so strongly argue against anything that smacks of Mother May I in roleplaying games. It's dysfunctional and leads to dysfunctional play.