Conciseness

The ~40-line body is lean and assumes Claude's competence: no explanation of what Build123d, V-slot, or a heat-set insert is; directives are terse ('Do not hand-model a screw hole, boss thread, or lead-in.') and the reference index table communicates per-file purpose in one row each. Every token earns its place, matching the 5 anchor; there is no padding that would drop it to 4.

Actionability

Guidance is concrete and executable for an instruction-only skill: a real import ('from screwjoint import make_screw_joint_v1'), a named rejection class ('ScrewJointNotApplicableV1'), specific read targets ('references/decision-guide.md'), and copy-the-recipe instructions. It is not 5 because the actual call contract for make_screw_joint_v1 and the connection-inventory mechanics are deferred to files that are not present in the bundle, leaving minor gaps a reader cannot resolve from the body alone; it is well above 3's 'pseudocode / missing key details'.

Workflow Clarity

The 7-step Core Workflow is clearly sequenced and includes an explicit validation checkpoint ('assert that every intended connection is handled by a named kit or by explicit freeform source') plus an error-recovery feedback loop (kit rejection → classify 'free' → model directly, with 'A ScrewJointNotApplicableV1 rejection is the only valid reason to model a joint by hand'). This matches the 5 anchor's 'explicit validation steps; feedback loops; checklists'; the operations are constructive CAD modeling, so the destructive/batch cap does not apply.

Progressive Disclosure

The body is well structured (overview, hard-constraint section, workflow, and a clear one-level-deep reference index table), but scored against the actual bundle: of the nine referenced paths, only the four references/*.md files exist — kits/printed-screw-joint-v1/KIT.md, both vslot-2020-corner-composite-v1 files, and both examples/*.py are absent. Since the Hard Constraint ('any screw fastening into a 3D-printed part') depends on the missing KIT.md, navigation to the skill's central content is broken, which is worse than the 4 anchor's 'minor organization gaps' and fits the 2 anchor's unusable-navigation end of the scale better than 3's 'could be better organized'.

Specificity

The description names the domain concretely ('standard mechanical parts, fasteners, bearings, V-slot rails, T-nuts, wheels, or linear-motion parts ... in Build123d CAD') and gives one concrete action ('printed screw joints must come from this skill's kit, never hand-modeled'), but it never states what the skill actually provides (pre-installed libraries, kits, recipes, an assembly workflow). It fits 'names domain and 1-2 concrete actions, but not comprehensive'; not 4 because no list of the skill's capabilities is given, and not 2 because the domain and the screw-joint rule are far more concrete than 'Processes PDF files'.

Completeness

The 'when' is explicit and excellent ('Use when standard mechanical parts ... are needed in Build123d CAD, and always before modeling a screw into a 3D-printed part'), but the 'what' is only implied — 'printed screw joints must come from this skill's kit' hints at a kit without saying the skill supplies library parts, kits, and recipes. Scoring only what is explicit, this matches 'what ... missing or only weakly implied' rather than the 4 anchor where both are present; the trigger clause keeps it well above 2.

Trigger Term Quality

Strong natural-term coverage: 'fasteners, bearings, V-slot rails, T-nuts, wheels, linear-motion parts, screw, 3D-printed part, Build123d CAD' are all phrases a user would naturally say. It falls just short of the 5 anchor ('comprehensive coverage including synonyms') because a few common synonyms are absent (e.g., 'bolts', 'nuts' beyond T-nuts, 'linear rails', 'shaft'); clearly above 3, which requires missing common variations.

Distinctiveness Conflict Risk

The description occupies a clear niche — Build123d CAD with V-slot rails, T-nuts, printed screw joints — with distinct trigger terms and minimal overlap risk with generic CAD or fastener skills. It matches the 5 anchor ('clear niche with distinct triggers; minimal conflict risk') and is far from the 4 anchor's 'minor overlap risk with closely related skills'.