Going through the current tag excerpts we have in place, I've begun to find that certain tags need certain things — not all (in fact not many) need usage guidance.
For example, I recently added an excerpt to wearable-technology simply stating what wearable technology is. No usage guidance or anything else.
Tags for a type of hardware/technology don't need usage guidance because if you're asking about something, you're going to tag what that something is. If you're asking about a computer monitor, you'll tag monitors. It seems pretty straight forward to me. These only need definitions.
However, tags for a property of hardware such as durability or waterproof should include usage guidance to clarify what they pertain to. I'm inclined to think these don't need definitions though.
These, 95 percent of the time, need their initials to be written out for clarity. Not a lot of people know what things stand for, even tech gurus (e.g., scsi). They'll need a definition, usage guidance, or both because they can be a property/feature of hardware (e.g., hdmi), hardware itself (e.g., ssd) or potentially both (e.g., gps).
I'm a very organized person, so this is something that catches my attention. I wouldn't put it at the top of the to-do list though.