Conciseness

The 37-line body is entirely operational — base URL, path preferences, param conventions, stdin contract, output fields, and one runnable bash invocation — with zero explanation of concepts Claude already knows (no "what UniProt is" padding). The one repeated example JSON (Input vs Execution) serves as a runnable end-to-end command, so every line earns its place; this fits the 5 anchor, not 4 (nothing reads as over-explanation to trim).

Actionability

Fully executable: three copy-paste-ready JSON payloads covering search, single-accession, and FASTA-stream cases, an exact `echo ... | python scripts/rest_request.py` invocation, explicit endpoint paths (`uniprotkb/search`, `uniref/<cluster>`, `uniparc/search`, `uniprotkb/stream`), and concrete param values (`size=10`, `fields`, `response_format=text`). The common cases are covered, matching the 5 anchor.

Workflow Clarity

This is a single-task skill (issue one API request and return a concise summary), and the single action is unambiguous: which script to use, which paths, how to size results, when to set save_raw and report the file path instead of pasting, and how failures surface (ok=false with error.code/error.message). Per the simple-skill exception this scores 5; the operations are read-only queries, so no destructive/batch validation cap applies.

Progressive Disclosure

The bundle is exactly SKILL.md + scripts/rest_request.py, the body references that one script path and it exists with a matching interface (max_items, save_raw, raw_output_path, response_format, ok/error envelope), and it explicitly states no further runtime references are needed. Under the under-50-lines simple-skill guideline, the well-organized sections (Operating rules / Execution behavior / Input / Output / Execution / References) merit the 5 anchor.

Specificity

"Submit compact UniProt REST API requests for UniProtKB, UniRef, UniParc, and FASTA stream endpoints" names the domain plus concrete capabilities across all four endpoint families, and "save raw JSON or FASTA only on request" adds a specific output behavior — comprehensive coverage in third person, matching the 5 anchor rather than 4 (no meaningful gaps for this niche).

Completeness

It clearly answers both: what ("Submit compact UniProt REST API requests for UniProtKB, UniRef, UniParc, and FASTA stream endpoints") and when ("Use when a user wants concise UniProt summaries"), with a concrete trigger phrase and an explicit output policy. Both clauses are explicit, matching the 5 anchor rather than 4.

Trigger Term Quality

Good natural-keyword coverage: "UniProt", "UniProtKB", "UniRef", "UniParc", "FASTA", "summaries" are terms users would actually say. A few natural variations are missing — e.g. "protein sequence", "protein database", or "accession" — so it sits at the 4 anchor rather than 5.

Distinctiveness Conflict Risk

"UniProt REST API" plus the named endpoint families define a clear niche with distinct triggers; virtually no other skill would fire on these terms, matching the 5 anchor (clear niche, minimal conflict risk).