Conciseness

The body is lean with no concept over-explanation, but the intro paragraph and the 'Scope of this skill' section state nearly the same thing twice ("It holds the SDK rules: API usage, UDF signatures..." vs "`SDK.md` owns how DataChain code is written — API usage, UDF signatures...") and "It is self-sufficient on its own" is filler — a small trim, matching the 'minor instances that could be trimmed' anchor rather than the fully lean anchor.

Actionability

Concrete, executable guidance throughout: named paths (`dc-knowledge/index.md`, `dc-knowledge/datasets/`, `dc-knowledge/buckets/`), a concrete check (`anon: true/false` in frontmatter), and a runnable command (`datachain bucket status <uri>`) with an explicit failure action. It falls short of fully executable because the authenticated-bucket path after detection is unspecified — no command or next step for the non-anon case.

Workflow Clarity

The 'Before writing any pipeline code' sequence is clearly numbered with an explicit error checkpoint ("If `denied` or `not found`, stop and ask the user") and a hard safety rule ("Never create or modify files under `dc-knowledge/`"). Anchor 5 is not met because the checkpoint only covers the failure branch — there is no validation of the success branch (what to do differently when `anon` is true vs false), leaving a minor validation gap.

Progressive Disclosure

A short, well-sectioned overview that delegates all SDK detail to a single one-level-deep, clearly signaled reference ("Read `{skill_dir}/SDK.md` in full") with an accurate scope summary of its contents, and clearly partitions responsibility with the sibling knowledge skill. No bundle files are present to inline incorrectly; navigation is unambiguous.

Specificity

Names the domain (DataChain SDK) and several concrete capability categories — "API usage, method signatures, or code patterns" — matching 'lists several specific actions; minor gaps'. It stays at 4 rather than 5 because it enumerates what kinds of questions qualify but never states the concrete actions the skill performs with them (answering questions, generating code).

Completeness

Explicitly answers both halves with concrete triggers: what/when via "Use ONLY for abstract DataChain SDK questions — API usage, method signatures, or code patterns — when no specific dataset or bucket is referenced", plus a negative boundary clause routing dataset/bucket work elsewhere. This is the 'clearly and explicitly answers both what AND when' anchor; anchor 4 would require the 'when' to be less explicit than the 'Use ONLY ... when no specific dataset or bucket is referenced' phrasing here.

Trigger Term Quality

Good natural keyword coverage — "DataChain SDK questions", "API usage", "method signatures", "code patterns", "dataset", "bucket" — phrases a user would plausibly say. Missing a few natural variants (e.g. 'how to use', 'UDF', 'Python library'), so it fits 'good keyword coverage; a few natural terms missing' rather than the comprehensive-synonyms anchor.

Distinctiveness Conflict Risk

Clear niche with minimal conflict risk: it carves out abstract SDK questions and explicitly disambiguates against the sibling skill ("If the request mentions creating, saving, listing, exploring datasets or buckets, use datachain-knowledge instead"), which is stronger than the 'mostly distinct; minor overlap risk' anchor 4 — the boundary is stated in both directions of the trigger.