I see in this question that in order to have the questions contain many features for the sake of matching some interpretation of the question guide lines, someone suggested to add having a GUI or being able to work on several files as required features. To me, that sounds pretty obvious, and it's pretty sure that if the OP wanted some CLI he would have said so. Does the OP have to mention obvious features?
While to you it is "pretty obvious" such a tool "needs" a GUI, that's not necessarily the case. I for example much more prefer a CLI for such tasks: Why should I take the hazzle having to start a (maybe even bloated) GUI, navigate to some folder (20 clicks or so), mark it, open some menu, find the right item, and click that to watch a fancy progress-dialog – when it would be so much easier from the shell with auto-complete to simply type something like
bpmtag Music/wherever <Enter>?
Standard phrase here: One man's owl is another man's nightingale. You might well guess wrong, based on your background. Not because the CLI case would be the more common (I'm fully aware of the fact it is not) – but simply because the OP thought it clear, as he always prefers it that way, and might simply have forgotten to include it ("If I wanted a GUI, I had said so" – as opposed to your POV).
There might be (and certainly is) a "gray zone" of what's really obvious. But it never hurts to draw the whole picture – as long as it doesn't go "War-and-Peace" ;)
Yes, as many things you consider important to you and are must have include them at all cost. We don't need people to be parse but verbose (and maybe greedy) when they are looking for something they will be using.
Please also note that in some cases there are just too many from where to pick and having some basic guidelines would be useful, in the case of this question:
The only restricted requirement is that it must run under Windows, and should be preferrably freeware.
There are many mp3 tag editors that fulfills both "must have", so narrow it down will help lots and OP won't have something he might not like.
This task is one where I would use a command line, scriptable application as a matter of course. I know that most people don't use the command line, so I suspected that a GUI was required. But it never hurts to explicitly say what you want.
If you don't specify a requirement because you consider it too obvious, and someone provides an answer that meets your expressed requirements but not what you had in mind, everybody's lost time. If you write it down explicitly, everything's good. So please do mention “obvious” requirements such as “must be GUI-driven”, “must run under Windows”, “must be free”, …