Conciseness

The body is lean and operational throughout — auth header format, endpoint, params table, a compact response example, one curl example, and terse error/degradation notes, with no explanation of concepts Claude already knows (no "what is an API/REST" padding). Matches anchor 5 ("every token earns its place"); anchor 4 would require visible over-explanation to trim, which is absent.

Actionability

The worked example is fully executable and copy-paste ready — a complete curl with the required X-WorldMonitor-Key header, URL-encoded query param, and a jq projection — alongside a concrete endpoint URL, params table, and a real response sample. Matches anchor 5 ("copy-paste ready... covers the common cases"); there is no pseudocode or missing key detail that would drop it to 4.

Workflow Clarity

This is a simple single-purpose skill whose single action is unambiguous (authenticated GET, then project the markets array), and it includes explicit checkpoints: error handling for 401 and 429 ("retry with backoff") and a degradation contract distinguishing "no data" from "no active markets". Under the rubric's simple-skill guidance this matches anchor 5; the operation is read-only, so the destructive/batch validation cap does not apply.

Progressive Disclosure

Sections are well organized (Authentication, Endpoint, Parameters, Response shape, Worked example, Errors, When NOT to use, References) with clearly signaled one-level-deep external references (OpenAPI operation, auth matrix), and nothing is buried or nested. However, the body runs ~81 lines — above the under-50-line simple-skill threshold that would let well-organized sections alone earn a 5 — so this sits at anchor 4 ("good structure; minor organization gaps") rather than 5.

Specificity

"Retrieve active prediction-market contracts (Polymarket) with live yes-price probabilities, volume, and close dates, filterable by category or keyword" lists multiple concrete actions with comprehensive field-level coverage of what is returned. Anchor 5 fits; score 4 would require identifiable coverage gaps, and none are present.

Completeness

It explicitly answers both questions: the "what" (retrieve contracts with yes-price probabilities, volume, close dates, category/keyword filtering) and the "when" ("Use when the user asks what the market odds are on a geopolitical, economic, or election outcome") with a concrete trigger phrase. This matches anchor 5; anchor 4 would require a less explicit "when" clause.

Trigger Term Quality

Natural phrases like "what the market odds are", "geopolitical, economic, or election outcome", and the named source "Polymarket" give good keyword coverage, but common user synonyms such as "betting odds", "chances of X", or "probability of" are missing. This matches anchor 4 ("a few natural terms missing") rather than anchor 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

"Prediction-market contracts (Polymarket)" with "market odds" triggers carves out a clear, distinct niche unlikely to fire for adjacent skills (e.g. model-generated forecasts). Matches anchor 5 ("clear niche with distinct triggers; minimal conflict risk"); it is not merely "mostly distinct" as in anchor 4.