wickedFauna said:
yes, in my experience the wildcard only works the way one would expect it to work when it's on both sides.
I may be stupid

represents 0-or-more-characters.

So searching *foo is asking for tags ending with exactly foo (eg. if there was a tag foo, that would be returned, but foot wouldn't)
and searching foo* is asking for tags beginning with exactly foo (In this case both foo and foot would be returned)
If you really want to search for 'tags WITH THIS FRAGMENT IN THEM', then *foo* is correct -- '>=0 characters, followed by "foo", followed by >=0 characters'

I think there is also no limit on amount of *.

(this is all standard glob-pattern convention, but IIRC e621 doesn't support the other parts of glob matching: ?:'exactly one character', and []: character classes, which is a whole thing )