In explaining logical possibility (broad), I tend to say that a thing is logically possible if it exists in some possible world, some possible description of reality, but in what sense is such a world/description of reality qualified as "possible"? In a broadly logical sense, of course. "Possible world"/"possible description of reality" could be replaced with "a way the world could have been," but there's still a tautologically-defined notion of possibility implicit in "could." Similarly for "a way the world might have been."
Does this semantic tautology actually show itself in modal logic discourse, and if not, what is the proper way to avoid it?