Conciseness

The body is dense and skill-specific (script flags, coordinate conventions, exit-code semantics, chemistry assumptions) and assumes domain competence — no basic-concept explanations. It falls short of a 5 because the computational-vs-experimentally-validated caveat recurs across several sections ("not a blanket claim of primer quality", "they do not validate a biological assay", "this is not empirical validation", "Label untested candidates accurately") where one consolidated statement would do, and version pins (primer3-py 2.3.1, Python 3.13, BLAST+ 2.17.0) appear inline rather than collected in one place. It is above a 3 because the over-explanation is minor relative to the volume of genuinely non-obvious operational guidance.

Actionability

Fully executable, copy-paste-ready commands with every flag and concrete file paths for design, thermodynamics, and both screening engines, plus a runnable demo ("--template "$SKILL_DIR/assets/demo-template.fasta" --preset qpcr --config ..."). Common cases are covered by presets (pcr 100–1000 bp, qpcr 70–200 bp), concrete chemistry values (--mv-conc 50 --dv-conc 1.5 ...), exit-code semantics (0/1/2), and per-field output interpretation (potential_off_target, incomplete, etc.).

Workflow Clarity

A clearly sequenced four-step workflow (design → thermodynamics → screening → validation/delivery) preceded by a request-routing table, with explicit validation checkpoints ("Inspect engine_explanations when no candidates are found", "Read the JSON scientific status even after exit 0") and feedback loops ("Change a biologically justified constraint and rerun", "resolve mapping, reference, sequence, and search problems before drawing specificity conclusions"). This matches the anchor-5 pattern of explicit validation steps with error-recovery loops.

Progressive Disclosure

The body is a workflow overview that delegates depth to one-level-deep, well-signaled references — each verified to exist — with purpose stated at the point of reference ("Read [specificity.md] before making a specificity claim", "Use [input-contract.md] for file schemas", "Read [thermodynamics.md] before interpreting these values"). Reference files cross-link only to sibling references and external URLs, with no buried nesting; content split (workflows, thermodynamics, specificity, input schemas, sources) is appropriate to the domain complexity. The only quibble is the prose mention of the upstream `tests/primer-design/` suite, which is not part of this bundle, but it is contextual rather than a navigation pointer.

Specificity

The description lists multiple concrete actions — "Designs and audits PCR and RT-qPCR primers with Primer3", "explicit thermodynamic conditions", "reference-based off-target amplification searches", "bounded local in-silico PCR and BLAST screening" — with comprehensive coverage of the skill's capabilities. It uses third-person voice throughout ("Designs", "audits"), so no voice penalty applies; it exceeds the anchor-4 example ("Extracts text from PDF files, fills forms, converts pages to images") in both breadth and concreteness.

Completeness

It explicitly answers both questions: the "what" ("Designs and audits PCR and RT-qPCR primers with Primer3, explicit thermodynamic conditions, reference-based off-target amplification searches, and traceable sequence coordinates") and the "when" via an explicit trigger clause ("Use for designing primer pairs, checking existing primers, exon-junction or isoform-specific assays, variant masking, cloning tails, multiplex compatibility, and interpreting Primer-BLAST results") with concrete trigger phrases. This is above the cap for a missing 'Use when' clause and matches the anchor-5 example pattern.

Trigger Term Quality

Natural user phrasing is comprehensively covered: "primer pairs", "PCR", "RT-qPCR", "exon-junction", "isoform-specific assays", "variant masking", "cloning tails", "multiplex", "Primer-BLAST" — exactly the terms a molecular-biology user would say when needing this skill. Tool-name synonyms (Primer3, Primer-BLAST) are included, and the domain has no meaningful file-extension trigger that is missing.

Distinctiveness Conflict Risk

A clear niche (oligonucleotide design/auditing for PCR and RT-qPCR) is anchored by distinct trigger terms (Primer3, RT-qPCR, Primer-BLAST, exon-junction), with explicit scope boundaries ("distinguishes computational candidates from experimentally validated assays") that further separate it from generic bioinformatics or sequence-analysis skills. Minimal conflict risk with adjacent skills.