Just a note that I can't repeat enough to relate some issues we went through on another of my SE sites. (I haven't checked anyone's new tag wikis so I'm not picking on anybody.)
All this advice is specifically about Usage guides (tag wiki "excerpts"). For the full tag wiki texts there are no severe space limitations (30,000+ characters are allowed) and no truncation issues so you can go wild with those. But it's still a good idea to be consistent.
When editing Usage guides, check the Tags page regularly. You will see that quite a few tags have their ends cut off and a few have the beginning cut off. Ideally we want to avoid this as much as possible. Two things are happening:
1. There is a length limit of ~500 characters. There's no place that tells us the exact limit so we have to keep checking to see that we don't go over it. (How many remain available does show.)
2. There is an algorithm that cuts out what it sees as unnecessary. This is often the part up to and including "is" or "are" and "This tag" when at the start.
So try to avoid tag excerpt text like
Amarillo is a city in Texas. Instead just go for
A city in Texas. - because the software will do it anyway and the result isn't always what you expect. For instance the initial capital letter will be lost.
Try to make the tags as much in the same style as possible. This makes our site look professional and slick. If unsure just look at a sample of other tags. If there are tags similar to yours (other cities, other airport codes) then look at those. If there is a pattern, use it.
- Start all excerpts with a capital letter and finish with a full stop.
The reason there are a bunch of tags like "Travel related to Germany." is for several reasons.
Stack Exchange has some tag wiki guidelines somewhere and they say to avoid definitions in tags.
I think Dori (SE staff) made some of these tags so they wouldn't be blank and wouldn't be definitions.
But I think for our particular SE site it doesn't make sense to stick too firmly to this rule as it results in redundant tags, which don't look professional at all.
After trying a few things for countries and some of them turning out pretty bad I suggest this:
For places you feel many people would not have heard of, a bit of definition is a good thing. Not everybody knows where the Pamir Highway is.
For places everybody does know try to list the one or two things that attract tourists. This can be tricky! Think of it as a writer's challenge - like writing a prose haiku!
For cities, I think at least including whether it is the capital, the biggest city, or both. Plenty of people don't realise LA is not the capital of California and Sydney is not the capital of Australia.