I notice that most of our tags descriptions begin 'Questions about', 'Questions regarding', 'Questions pertaining to', etc. This seems rather redundant as all tags are on questions. A look at https://stackoverflow.com/tags shows most begin 'a' or 'an', or often with a clarifying word. What format is most appropriate here? All so notice there is a discrepancy between starting the description with a capital (here) or lowercase (SO) letter.
I'm not sure if you're referring to tag wiki bodies or the tag wiki excerpts (short summary descriptions that display in the popup box when hovering over them)?
Tag wiki excerpt
The tag wiki excerpt is a brief plain text introduction to the topic that the tag represents. It is shown at the top of tag question lists, and as a tooltip wherever the tag appears.
Full tag wiki
The full tag wiki is a detailed introduction to the topic, suitable as a destination for those curious about it:
► what questions should have this tag?
► some basic definitions
► brief introduction to the subject
► important links for learning more
► one reasonably sized page
See our advice on writing great tag wikis.
If you meant the tag excerpts, then with the exception when adding this intro to the tag excerpt would make the text too long to fit the box, I don't see why not. Tags, wherever they're posted, always link to the list of questions filtered by the tag or its tag synonyms. The only notable exception is, when a user clicks on the tag info and displays the whole tag wiki (both an excerpt and the longer tag wiki body, if it exists), but even then, I personally don't think it is harmful to their appearance or misinterpreting their function.
I.e. the use of 'Questions about', 'Questions regarding', 'Questions pertaining to', e.t.c. is semantically correct, since the click on the tag in question results in displaying the list of questions tagged as the one that was clicked on (and its synonyms). This behaviour is the same throughout Stack Exchange, and doesn't matter if tags are displayed under questions, comments, or even in chat rooms.
So in short, I don't think we should enforce some single format, or that there are clear advantages to any to warrant their recommended use. Descriptions should be written to describe the meaning of the tag in a concise way in their excerpts, and possibly further clarify their meaning in the longer tag wiki bodies.
Here’s a few words of advice on writing tag wiki excerpts:
- The excerpt is the elevator pitch for the tag. You only have ~500 plain text characters for the excerpt, so don’t feel obligated to cover everything in it! Save that for the 30,000+ character Markdown tag wiki. The excerpt should define the shared quality of questions containing this tag — boiled down to a few short sentences.
- Avoid generically defining the concept behind a tag, unless it is highly specialized. The “email” tag, for example, does not need to explain what email is. I think we can safely assume most internet users know what email is; there’s no value in a boilerplate explanation of email to anyone.
- Concentrate on what a tag means to your community. For “email” on Server Fault, mention the server aspects of email including POP3, SMTP, IMAP, and server software. For “email” on Super User, mention desktop email clients and explicitly exclude webmail, as that would be more appropriate for webapps.stackexchange.com.
- Provide basic guidance on when to use the tag. In other words, what kinds of questions should have this tag? Tags only exist as ways of organizing questions, so if we don’t provide proper guidance on which questions need this tag, they won’t get tagged at all, rendering the tag excerpt moot. Think of it as a sales pitch: in a room full of tags screaming “pick me!”, what would convince a question asker to select your tag?
- Some tags are common knowledge. Most tags require a bit of explanation in the excerpt, even if it’s only 3 or 4 words. But if the tag is common knowledge — that is, if you walked up to any random person on the street and said the tag word to them, and they would know what you were talking about — then don’t bother explaining the tag at all. Stick to usage of the tag within your community in the excerpt.