Your line that the description "has to say both what the skill does and when to reach for it" matches what I see at scale. Disclosure: I run Skillselion, a directory that indexes tens of thousands of public SKILL.md files, and vague descriptions are the most common defect I see in the wild, exactly as your linter ranking suggests. Two candidate rules for skillmd-lint's list, drawn from that corpus: first, a license check. The overwhelming majority of public skills declare no license at all, which quietly blocks the fork-and-adapt loop your "read it as if it were code" advice depends on. Second, a trigger-phrase check: descriptions that state what but never when, since those register fine and then never fire. Your injection-shaped-content story about the comedy skill rejected over the word "secretly" is a genuinely useful data point about marketplace scanners. Is the seven-mistake ranking published anywhere with frequencies? That distribution would be worth citing.