FWIW, I agree mostly with bukayeva; I think maga is over-correcting. Consider (if you please) the following hypothetical game transcripts:
Each response gives a slightly different flavor to the rest of the game, I agree — and I think this is what maga means by saying that “x me” contributes to characterization. But as bukayeva says, it doesn’t contribute a really significant amount; take whatever game you’re imagining from one of the first few transcripts above, and now imagine that same game with “x me” giving Inform’s default flippant response. It’d break the immersion a bit, right? but it wouldn’t cause the quality of the entire game to suffer noticeably.
The response to “x me” can vary wildly in its contribution to characterization, too. I think that first transcript would be an indicator of a decently written game, don’t you? But delete the last two sentences and it becomes (for me) worse than nothing. I would vastly prefer to see either of the last two responses than any of the three before them. Chekov’s Gun again — if the response to “x me” is actually useful and helpful in my understanding of the puzzle and/or story, then great; but if it’s just written out of a sense of obligation, I’d rather not see it at all.
This is turning into an interesting discussion on “x me”, so I’m not sure if I should derail it by admitting that “sing” (“jump”, etc.) is a much worse offender than “x me”. I think we might end up all agreeing on that point!
Again, each response contributes a certain amount of characterization. It’s very much tied up with the “player-protagonist-narrator” trinity, though; some of these responses tell you more about the protagonist, some tell you more about the narrator. I’m particularly not a fan of responses #2 (the Inform default) and #4 (“You’d rather not.”), because they demonstrate a conflict between the player and the narrator/commentator, which reads to me as a conflict within the protagonist. The PC is going about his business when suddenly he has an urge to sing — but before he can act on it, it’s squelched by an inner policeman. This is characterization too, but it’s usually not the sort of characterization that the IF author intended. Response #5 is superior because it pushes the squelching all the way up to the parser level; I can now write for a PC who never has sudden urges to burst into song. Response #3 (presumably in an interactive Ruddigore) strikes me as unobjectionable, because the commentator seems to be playing along with the player, rather than bluntly or dismissively squelching his command.
IOW: If your protagonist is stodgy Mr Banks who never wants to sing, then you should remove the verb “sing” at the parser level. If your protagonist is repressed Mr Banks who feels it would not be proper for a respectable bank manager to break into song, then you should provide an appropriate response at the narration level. If you handle it at the wrong level, I will notice, and it will irk me.