I think it's a perfectly good tag, though perhaps responses would be a better name.
By the time you read this, it's quite possible What is the difference between “nope” and “no”? will also have the tag (it certainly seems like a good example to me).
There might also be merit in using the tag for those questions asking whether some specific "sentence" is "grammatical" or not, when the example presented is simply a "cut-down" response to a preceding question or statement. I have an open mind on that point, but it's worth noting that ELU has a headline-english tag that may indicate (among other things) that "normal standards of grammar may not apply".