Conciseness

The ~40-line body is dense, directive prose with zero concept explanations and no padding — every sentence carries a constraint ("Preserve existing entities, IDs, native guards and provider-managed state/defaults", "add storage only for a demonstrated gap", "no owner column at every step, team/role engine or mirrored billing ledger by default"). It fully assumes Claude's competence and every token earns its place, matching the lean-and-efficient top anchor.

Actionability

The five steps name concrete artifacts to act on ("trace the affected entities, IDs, auth, credentials, queries and workers", "check the affected happy path, cross-owner denial") and the worked example is executable in form (mapping "GET/PATCH /projects/:projectId/notes/:noteId" onto "requireOwnedProject(actor, projectId)" with concrete owner-A/owner-B checks). It falls short of fully executable because the actual contract specifics are deferred to referenced spec files rather than given in the body — minor gaps, not the missing-key-details of level 3.

Workflow Clarity

Clear five-step sequence (Inspect, Map, Resolve, Record and act, Verify and report) with explicit validation checkpoints — "check the affected happy path, cross-owner denial and applicable repeat/failure recovery" — an explicit feedback loop ("If a check fails, correct the bounded mapping/implementation and rerun affected checks"), plus error-recovery and honest-reporting rules ("Report actual results or mark checks unrun"). This matches the top anchor including feedback loops for error recovery, so the level-4 anchor with minor validation gaps does not apply.

Progressive Disclosure

Structurally the overview is exemplary — clearly signaled, conditionally scoped, one-level references ("Read only the relevant contracts", user-choices "only when affected") — but scored against the actual bundle, all 13 relative link targets (specs/identity.md, ownership, connections, background-work, subscriptions, credits, management, user-choices, lifecycle, MODELS.md, BRIDGE-PLAN.md, examples/personal-mailbox-app.md, examples/paid-personal-app.md) resolve to no file present, and the bundle's own scripts/check_skill_bundle.py --review-scope would flag every link as missing. Navigation to the deferred detail is therefore non-functional, which lands at level 2 (references effectively unusable): not level 3+, since the referenced content the structure depends on is unavailable in the shipped bundle, and not level 1, since SKILL.md itself is well organized with clearly labeled references.

Specificity

The description states one concrete action — "Map private customer access onto an existing personal app" — plus generic deliverable nouns ("a short host-specific plan, implementation guidance and checks"), matching the anchor that names the domain with 1-2 concrete actions but is not comprehensive. It stays below the "lists several specific actions" level because the seven enumerated feature areas (login, isolation, billing, credits, admin screens) function as triggers rather than distinct actions.

Completeness

Explicitly answers both questions: what — "Map private customer access onto an existing personal app with a short host-specific plan, implementation guidance and checks" — and when — "Use when login/authentication, multi-tenant isolation, customer-owned connections, background imports, subscription billing, service credits or admin screens need connecting to existing entities and workflows." This matches the top anchor: clear what AND when with concrete trigger phrases, so the level-4 anchor ('when' could be more explicit) does not apply.

Trigger Term Quality

Good natural-term coverage with synonym pairing: "login/authentication", "multi-tenant isolation", "customer-owned connections", "background imports", "subscription billing", "service credits", "admin screens". A few common variations a user might say (e.g. "pricing", "per-tenant data", "billing webhooks") are missing, so it fits good-but-not-comprehensive keyword coverage rather than the comprehensive-with-synonyms top anchor.

Distinctiveness Conflict Risk

Clear niche — grafting customer-access features onto an existing personal app rather than building new ones — with distinct triggers, and the explicit boundary "Skip new-app scaffolding and SDK mechanics whose host mapping is already solved" separates it from scaffolding/SDK skills. Minimal conflict risk, matching the clear-niche top anchor.