Conciseness

The ~37-line body is all operational guidance — base URL, endpoint preferences, stdin JSON contract, output fields, one runnable command — with no explanation of concepts Claude already knows (no "what is a REST API" padding). Every bullet carries non-inferable, fragile-upstream knowledge; anchor 5 fits, and anchor 4's "minor instances of over-explanation" don't apply.

Actionability

The Execution section gives a copy-paste-ready bash command and the Input section lists three complete, executable JSON request objects covering the common cases (list studies, association by gene+rsid, legacy per-gene associations), plus an explicit required/optional field contract. This matches anchor 5; nothing is pseudocode or high-level.

Workflow Clarity

This is a simple single-purpose skill (one action: echo a JSON request into scripts/rest_request.py) and that action is unambiguous with the exact command shown, so the simple-skill exception applies. Checkpoints are also present for the fragile upstream: "surface upstream 400/500 errors verbatim when they occur", "Failure returns ok=false with error.code and error.message", and "Re-run requests in long conversations" as a retry loop. The destructive/batch cap does not apply — the operation is read-only retrieval bounded by max_items.

Progressive Disclosure

Under 50 lines with well-organized sections (Operating rules, Execution behavior, Input, Output, Execution, References) and a single one-level reference to scripts/rest_request.py, which exists in the bundle and whose interface matches the body's claims (variant_id→snp mirroring, filter backfills, save_raw/record_path). The References section explicitly bounds the import package, so the structure guideline for short skills with no external references is fully met.

Specificity

"Submit compact eQTL Catalogue API requests for association retrieval and documented metadata endpoints" names the domain and two concrete actions (association retrieval, metadata endpoints), but stops there — matching anchor 3 rather than 4, which requires several specific actions with only minor coverage gaps.

Completeness

Both parts are present: the "what" ("Submit compact eQTL Catalogue API requests for association retrieval and documented metadata endpoints") and the "when" ("Use when a user wants concise public eQTL Catalogue summaries"). The "when" is explicit but narrow — it doesn't mention retrieving associations by gene or variant, the most common use — so it matches anchor 4 (when could be more specific) rather than 5's concrete multi-phrase triggers, and clearly not 3 since the when-clause is explicit, not weakly implied.

Trigger Term Quality

Relevant keywords like "eQTL Catalogue", "association", and "summaries" are present, but common variations users would naturally say are missing — "eQTL", "QTL", "gene expression", "variant/SNP", "genotype". This fits anchor 3 (some relevant keywords, missing common variations and synonyms) better than 4's "a few natural terms missing", since the omission is broad.

Distinctiveness Conflict Risk

"eQTL Catalogue" names a specific EBI resource with a distinct niche (public eQTL association data); no other plausible skill shares these triggers, matching anchor 5 (clear niche, distinct triggers, minimal conflict risk).