The ~35-line body is lean, single-purpose, and assumes Claude's competence — it explains no concepts and delegates shared material to one-level-deep references rather than duplicating it, with only minor verbatim repetition of the 'tool not available' instruction.

It names concrete tools (@Sites, @Vercel), gives an exact question to ask, and orders steps, but the core action of actually running the deployment is delegated to external tool skills with no executable commands or detail on detecting availability, fitting the 'some concrete guidance but incomplete' anchor.

The 8-step sequence is clearly ordered with explicit decision branches (target chosen vs. not, tool available vs. not) and an explicit verification gate ('Do not claim the prototype is shared until you have a working URL') plus a recovery path for unavailable tools.

Content is well-organized into clearly labeled sections and uses well-signaled, one-level-deep references (Plugin router, critical-overrides, user-context) for shared material; as a simple under-50-line skill with no local bundle files, this meets the level-3 anchor.

"Share a runnable prototype using the user's preferred deployment tool" names a concrete domain (prototype deployment) and one action (share/deploy), but does not list multiple specific concrete actions like the level-3 anchor requires.

It clearly states what the skill does (share/deploy a prototype), but there is no explicit 'Use when...' clause or equivalent trigger guidance, so 'when' is only implied — the rubric caps completeness at 2 in that case.

"Share" and "deployment tool" are natural terms a user might say, but common variations such as deploy, publish, host, or put online are missing, matching the 'some relevant keywords but missing common variations' anchor.

The combination of 'runnable prototype' and 'deployment tool' carves a clear niche (deploying prototypes to a hosting target) that is unlikely to trigger for unrelated skills, matching the clear-niche anchor.