Conciseness

The ~50-line body is lean and every line is instructive — type-token guidance ('one clean sans like Inter / system-ui'), the accent-color rule ('use it ONLY for the numbered pins... everything else stays greyscale'), and the output contract. No padding and no explanations of concepts Claude already knows, matching anchor 5.

Actionability

The guidance is concrete and directly executable for an instruction-only skill: a named block-by-block layout with pin assignments ('Top nav... Pin ①' through 'Footer... Pin ⑤'), worked spec-note examples ('① Sticky nav, 64px, condenses on scroll'), data-od-id marking, and an exact artifact output format. Anchor 5 applies; anchor 4 would require minor gaps in the concrete guidance, and the five-block structure plus output contract covers the common case fully.

Workflow Clarity

A five-step sequence ends in an explicit validation step ('**Self-check**: Every numbered pin on the canvas has exactly one matching spec row') with a checklist covering pin/row parity, accent-color usage, thumbnail legibility, and style compliance. This matches anchor 5 (clear sequence with explicit validation steps and a checklist); the destructive/batch cap does not apply since this is a single generative task.

Progressive Disclosure

The skill is under 50 lines, single-purpose, with no bundle files (no references/, scripts/, or assets/ exist), and the body is cleanly sectioned into Workflow, self-check, and Output contract. Per the simple-skill scoring note, this earns anchor 5 on well-organized sections alone.

Specificity

The description enumerates multiple concrete capabilities: 'a desktop landing/marketing page drawn as flat greyboxes inside a browser chrome frame, overlaid with numbered annotation pins (①②③④⑤) in a single accent color, paired with a right-hand SPEC PANEL that lists each numbered pin with a short engineering / UX note'. Coverage is comprehensive with no gaps, matching the anchor-5 example rather than anchor 4 (which requires minor gaps).

Completeness

Both questions are answered explicitly: a detailed 'what' (annotated redline wireframe with greybox canvas and spec panel, plus style constraints 'NOT hand-drawn') and a concrete 'when' ('Use when the brief asks for...') with trigger phrases. This mirrors the anchor-5 example structure; anchor 4 would require the 'when' to be less explicit, which it is not.

Trigger Term Quality

The 'Use when' clause lists comprehensive natural trigger phrases with synonyms and variants: 'annotated wireframe', 'redline wireframe', 'wireframe with spec', 'lo-fi landing wireframe', 'low fidelity', '线框图', '标注线框', 'redline'. This matches anchor 5 (comprehensive natural-term coverage including synonyms).

Distinctiveness Conflict Risk

The description carves out a clear niche with a disambiguation clause ('This is the "wireframe + redline spec" style — clean, flat, low-fidelity, NOT hand-drawn') and mostly distinct triggers, but the generic terms 'wireframe' and 'low fidelity' in the trigger list carry some overlap risk with other lo-fi design skills. This sits between anchor 4 (minor overlap risk) and anchor 5, closer to 4.