Every `SKILL.md` declares a license
Installers extract one skill directory at a time. The repository license file does not travel with it, so an extracted skill arrives with no terms attached and nobody downstream can tell whether they may use it.
Observable check
the frontmatter of every skills/*/SKILL.md carries a license: field naming the license that applies to that skill. It matches the repository license when that license covers the skill; a differently licensed skill carries its own license file and the field references it.