I find that even though this isn't standard, that these -cli tools will scan the repo for .md files and for the most part execute the skills accordingly. Having said that, I would much prefer standards not just for this, but for plugins as well.
>>pretty+(OP)
Standards for plugins makes sense, because you're establishing a protocol that both sides need to follow to be able to work together.
But I don't see why you need a strict standard for "an informal description of how to do a particular task". I say "informal" because it's necessarily written in prose -- if it were formal, it'd be a shell script.