Conciseness

The ~30-line body is lean with zero padding: every paragraph contributes novel instruction (rounds, frontier, question format, fact-vs-decision division of labor, termination condition) and nothing explains concepts Claude already knows. This matches anchor 5 ('lean and efficient; every token earns its place') and is above anchor 4, which would require trimmable over-explanation that is absent here.

Actionability

As an instruction-only skill, the guidance is fully concrete: an exact copy-paste round template (numbered questions, bold titles, recommended-answer arrows, '---' separators), an explicit wording rule ("Word each question so 'yes' accepts your recommended answer"), and unambiguous rules for dispatching sub-agents for facts. This matches anchor 5 ('fully executable... specific examples cover the common cases') per the rubric's code-vs-instruction note, and exceeds anchor 4 because no execution gaps remain.

Workflow Clarity

The multi-step process is explicitly sequenced with a feedback loop: compute the frontier, ask the whole frontier in one numbered round, wait for answers, recompute the frontier from settled decisions, and repeat. Validation checkpoints are explicit — the session ends only when the frontier is empty ("nothing left silently assumed") and "Do not act on it until the user confirms". This matches anchor 5 ('clear sequence with explicit validation steps; feedback loops') rather than anchor 4, which requires missing checkpoints.

Progressive Disclosure

The skill is under 50 lines with no external references needed and no bundle files exist, so per the rubric's simple-skill note it can score 5 on well-organized content alone. The body progresses logically (concept → format → sequencing rules → fact-finding → termination) with an isolated, clearly-signaled format block, matching anchor 5 rather than anchor 4, which would require organization gaps.

Specificity

The description names one concrete action — "Grill the user relentlessly about a plan, decision, or idea" — with a clear target, but lists no further specific actions (e.g., asking numbered questions, recommending answers, mapping a design tree). This matches anchor 3 ('names domain and 1-2 concrete actions, but not comprehensive') and falls short of anchor 4, which requires several specific actions; it is above anchor 2 because 'grill relentlessly' is concrete rather than generic.

Completeness

Both halves are explicitly answered: the 'what' is "Grill the user relentlessly about a plan, decision, or idea" and the 'when' is "Use when the user wants to stress-test their thinking, or uses any 'grill' trigger phrases", with concrete trigger phrases present. This matches the anchor 5 example structure (clear what + explicit when with concrete triggers) and is above anchor 4, where the 'when' would be less specific.

Trigger Term Quality

It includes two strong natural trigger terms — "stress-test their thinking" and "'grill' trigger phrases" — but misses common synonyms and variations users would say, such as 'pressure-test', 'challenge my plan', 'poke holes in my reasoning', or 'devil's advocate'. This fits anchor 3 ('some relevant keywords but missing common variations or synonyms') rather than anchor 4, which expects good coverage with only a few terms missing.

Distinctiveness Conflict Risk

The grill/stress-test niche is distinct with a memorable trigger word unlikely to fire the wrong skill, but the broad object scope ('plan, decision, or idea') leaves minor overlap risk with general planning, review, or critique skills. This matches anchor 4 ('mostly distinct; minor overlap risk') rather than anchor 5, which demands minimal conflict risk.