Conciseness

The ~25-line body contains zero padding and no explanations of concepts Claude already knows — the brief framing sentence ('tribal knowledge (architecture, data flows, type mappings, pitfalls)') is the only context and it directly motivates the workflow. Every token earns its place, matching the 'lean and efficient' anchor.

Actionability

Each step is fully executable: exact directory names ('.github/skills/'), a concrete path-to-package example ('sdk/search/Azure.Search.Documents/src/SearchClient.cs' → 'sdk/search/Azure.Search.Documents/'), and a CODEOWNERS fallback when only a package name is known. Per the rubric's instruction-skill note, absence of code is not penalized when guidance is this concrete.

Workflow Clarity

The four steps are clearly sequenced with an explicit decision branch (skill directory exists → read all SKILL.md and references/; not exists → 'proceed normally'). This is a read-only discovery operation, so no validation/feedback loops are required, and the sequence with its branch handling is unambiguous — matching the simple-skill allowance for a 5.

Progressive Disclosure

The skill is under 50 lines with no bundle files (no references/, scripts/, or assets/ exist) and no need for external references; the two well-organized sections (intro + 'How to Discover Package Skills') satisfy the rubric's simple-skill exception for a top score.

Specificity

The description names its domain ('packages under sdk/') and exactly two concrete actions ('Discovers and loads package-specific domain knowledge that prevents common mistakes'), which matches the anchor for 1-2 concrete actions. It does not list several specific actions, so anchor 4 does not fit.

Completeness

Both halves are explicit: the what ('Discovers and loads package-specific domain knowledge that prevents common mistakes') and the when ('Must be consulted before making any changes to packages under sdk/' plus 'WHEN: add feature to package; fix bug in package; …') with concrete trigger phrases — an exact match for the top anchor.

Trigger Term Quality

'add feature to package; fix bug in package; modify package code; regenerate from typespec; change client library' gives good natural keyword coverage a user would actually say. It is not comprehensive — synonyms like 'update', 'refactor', or 'work on the SDK' are missing — so it sits at anchor 4 rather than 5.

Distinctiveness Conflict Risk

The description is scoped to a clear niche — 'packages under sdk/' with 'typespec' and 'client library' triggers — making it unlikely to fire for unrelated skills and giving it minimal conflict risk, matching the top anchor.