Conciseness

The body assumes Claude's competence — it never explains what arbitrage, order books, or exchanges are — and every section adds skill-specific information: exact commands with flag semantics, fee-source caveats ("KuCoin and Coinbase do not show a base-tier fee without a login, so their net column reads `n/a`"), and an exclusion list. This matches anchor 5 ('lean and efficient; every token earns its place'); anchor 4 would require over-explanation that could be trimmed, and none is evident.

Actionability

Every command is copy-paste ready with real flags, sample output, and an offline `--demo` path, covering scan, fees, sizing, triangular, and monitor use cases — near anchor 5. However, the Resources section points to a test suite ("python3 -m unittest discover -s tests -v") whose `tests/` directory is absent from the bundle, a minor gap that fits anchor 4 ('concrete commands with minor gaps') better than 5.

Workflow Clarity

The numbered Instructions sequence each operation unambiguously, and the Error Handling table provides explicit feedback loops — message → cause → what to do (e.g., "no confirmed fee for kucoin" → "Pass `--fee kucoin=PERCENT`") — plus exit-code semantics and a reporting contract. For a read-only skill with no destructive or batch operations, this matches anchor 5's explicit validation and error-recovery structure; anchor 4's 'minor validation gaps' is not supported.

Progressive Disclosure

SKILL.md is a clean overview whose details are appropriately split into three one-level-deep references, all present in the bundle and clearly signaled inline ("More in [`references/errors.md`]", "Details: [`references/implementation.md`]", full runs in `references/examples.md`) and again in a Resources section. This matches anchor 5; no content that belongs in a reference is inlined and no nested references exist.

Specificity

The description lists multiple concrete actions — "Compare live best bid and ask for one crypto pair across exchanges", "report every cross-venue spread, gross and net of stated taker fees", "search three-trade cycles within one exchange", plus the explicit constraint "Read-only, no API keys" — with comprehensive coverage of the skill's capabilities. Anchor 5 (multiple specific concrete actions, comprehensive) matches directly; anchor 4 requires 'minor gaps in coverage' and no such gap is evident.

Completeness

It explicitly answers both questions: the first paragraph states what the skill does, "Use when checking whether a coin trades at different prices on different exchanges, sizing a spread against fees, or looking for triangular price gaps on OKX, KuCoin or Gate" states when, and concrete trigger phrases are listed. This mirrors the anchor 5 example's structure (what + when + explicit triggers); a 4 would require the 'when' to be less explicit.

Trigger Term Quality

The trigger list "find arbitrage", "scan for arb", "price spread", "exchange price difference", "triangular arb", "cross-exchange spread" covers natural phrasings, abbreviations ("arb"), and synonyms a user would actually say. This matches anchor 5's comprehensive coverage including synonyms; anchor 4 ("a few natural terms missing") does not fit since no common variation is obviously absent.

Distinctiveness Conflict Risk

The crypto cross-exchange arbitrage niche is distinct, with venue names (OKX, KuCoin, Gate) and domain-specific triggers that no generic skill would claim. Minimal conflict risk, matching anchor 5 ('clear niche with distinct triggers'); anchor 4's 'minor overlap risk with closely related skills' is not supported since no sibling skill is plausibly confusable with these triggers.