Conciseness

The body is mostly efficient — application tables, copy patterns, and checklists are dense — but includes unnecessary explanation: four "Why it works" paragraphs re-explain psychology Claude already knows (dopamine anticipation, the IKEA effect, Fogg's model, Hick's Law), and the closing "About the Author" biography and affiliate-linked "Further Reading" section are pure padding. It fits anchor 3 (mostly efficient, some unnecessary explanation) better than anchor 4, since multiple whole sections could be cut without losing operational value.

Actionability

For an instruction-only skill, guidance is concrete: specific product examples ("Duolingo: play first, create account later"), exact copy patterns ("3 people responded to your post"), a diagnostic table mapping question → failure signal → action, and a 0-10 scoring directive with required output. It stops short of fully copy-paste-ready recipes (habit-testing methodology is deferred to a reference without an inline quick-start), matching anchor 4.

Workflow Clarity

The Hook cycle is clearly sequenced (Trigger → Action → Variable Reward → Investment with a loop diagram), and the Onboarding Audit Checklist provides phase-by-phase checkpoints (First Trigger → First Action → First Reward → First Investment → Loop Completion). Not anchor 5 because there is no explicit validate → fix → retry feedback loop (e.g., the habit-testing questions are given but the iteration path lives in a reference), leaving minor checkpoint gaps.

Progressive Disclosure

Good structure against the actual bundle: all 7 referenced files exist, references are one level deep (verified: reference files contain only internal TOC anchors, no nested file references), and each phase links contextually ("See: [references/triggers.md]...") plus a consolidated Reference Files section with one-line descriptions. It falls short of anchor 5 because the ~295-line body inlines substantial per-phase detail (full application tables and copy patterns for all four phases) that could live in the reference files, leaving SKILL.md heavier than a lean overview.

Specificity

The description lists several concrete actions — "Design habit-forming product loops using the Hook Model (Trigger, Action, Variable Reward, Investment)", "Covers ethics evaluation and onboarding", "analyzing why users stop using a product after initial signup", "building streaks or progress systems" — with minor gaps (e.g., "covers" is softer than naming a concrete deliverable). It sits between anchor 3 (1-2 concrete actions) and anchor 5 (comprehensive, fully concrete action list), so 4 fits best.

Completeness

It explicitly answers both questions: what ("Design habit-forming product loops using the Hook Model... Covers ethics evaluation and onboarding") and when ("Use when the user mentions..." plus "Also trigger when designing notification strategies...") with concrete quoted trigger phrases. This matches the anchor-5 example structure exactly; the when clause is explicit, not merely implied.

Trigger Term Quality

Includes many natural phrases users would actually say — "users arent coming back", "engagement loops", "habit formation", "push notifications", "variable rewards", "daily active users", "habit zone", "user retention loops" — which is strong coverage. A few common synonyms like "churn", "stickiness", or "re-engagement" are missing, keeping it at anchor 4 rather than 5.

Distinctiveness Conflict Risk

The niche is clear (Hook Model habit formation) with distinct triggers, and it explicitly disambiguates sibling skills: "For friction reduction and B=MAP, see improve-retention. For viral sharing, see contagious." That explicit boundary-setting gives minimal conflict risk, matching anchor 5.