I came across description of tags at the following convention (I took badminton as an example):
Questions about rules, equipment and training related to badminton.
I think that an Excerpt about tag should be a real explanation of the tag and not a general convention as above.
We all know this web site design for questions so i think that the explanation should be like this (again I took badminton as an example):
Badminton is a racquet sport played by opposing players who take positions on opposite halves of a rectangular court that is divided by a net. Players score points by striking a shuttlecock with their racquet so that it passes over the net and lands in their opponents' half of the court.
What do you think?