One of the more confusing things about this site is the hard-science tag. Looking through the meta site, there aren't a lot of clear policies surrounding the tag.
One particular problem I have is that there are a lot of questions tagged as hard-science where the OP seems to have used the tag by mistake. For example, the question Would a 'World Tree' be feasible in real life? is tagged as hard-science, but a quick look through the comments shows that the OP isn't actually looking for hard science answers. So it seems reasonable to assume that the hard-science tag should be removed.
I would like to go through the hard-science tag and remove questions like that. I think doing so would make the purpose of the tag clearer to new users, and it would also make it easier for people who like real hard-science questions to find them.
But in a lot of cases it's not as clear cut whether a question is incorrectly tagged or not. For example, the question Could my moons-planet system be stable?: the answers don't meet the hard-science requirements, and the question is so simple I'm not sure it even needs hard-science answers, but the OP didn't really do anything to indicate that they used the tag by mistake. So maybe they're still waiting for an answer that meets the hard-science requirements?
What I'm asking for is a clear set of guidelines to determine whether a question should be tagged as hard-science or not. There has been a little bit of discussion on meta here and here and here, but there really isn't a specific guideline that someone could use to retag questions.
(Also, speaking of tagging, could someone create a hard-science tag on the meta site? This would make it easier to find all the policies related to the hard-science tag.)