Conciseness

The body explains nothing Claude already knows — every line is an MPS-specific gotcha ("the `infer` prefix makes an inequation *soft* … will not immediately error", "**always wrap the real Expression in a `NormalTypeClause`**", "Quick fixes … are roots, **not** executed automatically") or a pointer. Matches anchor 5 ("Lean and efficient; assumes Claude's competence; every token earns its place"); the only near-duplication (the `List<SNode>` → `sequence<node<X>>` pointer appearing in both Critical Directives and Related Skills) is cross-referencing in two navigational contexts, not padding.

Actionability

Gives copy-adaptable commands with exact parameters: "`mps_mcp_create_model` with `moduleName: \"<lang>\"` and `modelName: \"<lang>.typesystem\"`", "`mps_mcp_apply_intention(nodeReference = <problem node>, intentionId = <fix id>)`", "MAKE with `parameters` = `{\"modules\":[\"<lang>\"],\"rebuild\":true}`", and the executable statement form `error "Expected " + <expectedType> + " but got " + <actualType> -> node;`. Matches anchor 5 ("Fully executable; copy-paste ready code or commands; specific examples cover the common cases") — common cases are routed to concrete reference files rather than left abstract.

Workflow Clarity

The 0–9 workflow has explicit validation checkpoints and a feedback loop: step 3 takes a baseline ("**Before** the change: `mps_mcp_check_root_node_problems` + `EXPLAIN_TYPE` … so you have the baseline error"), step 5 re-verifies after ("**After**: ask again — `IS_SUBTYPE` … `EXPLAIN_TYPE`"), step 8 validates, and step 9.6 cleans up the scratch model. Matches anchor 5 ("Clear sequence with explicit validation steps; feedback loops for error recovery"), not 4 — the checkpoints are explicit before/after gates, not implicit.

Progressive Disclosure

The Reference Index opens with task-based routing ("**Start here — most common case**: one `InferenceRule` that types a concept → read only `references/inference-rules.md` …") and each reference entry states both what it contains and when to open it ("Open `references/when-concrete.md` when a rule must wait for a resolved concrete type"). References are one level deep and clearly signaled, matching anchor 5 ("Clear overview with well-signaled one-level-deep references; content appropriately split; easy navigation"). No bundle files were provided for structural verification, so this is scored on the body's structure; the only wrinkle — the cross-skill `type-queries.md` pointer appearing inline rather than in the index — is signaled at its point of use.

Specificity

Enumerates concrete, specific capabilities — "inference rules (`typeof :==: / :<=: / :>=:`)", "`SubtypingRule`, `ComparisonRule`, `InequationReplacementRule`, `SubstituteTypeRule`", "error/warning/info reports with `messageTarget` highlighting and quick-fix wiring (`helginsIntention`)", "shared BaseLanguage helpers", and compiled-typesystem queries (`IS_SUBTYPE`, `EXPLAIN_TYPE`, `GET_EXPECTED_TYPE`). This matches the anchor "Lists multiple specific concrete actions; comprehensive coverage" — it is not a 4 because there are no minor gaps: authoring, debugging, checking, quick-fix wiring, and query-side debugging are all named.

Completeness

Explicitly answers both questions: the "what" is the enumerated capability set ("Use when authoring or debugging MPS typesystem — inference rules … `TypesystemQuickFix`, error/warning/info reports …") and the "when" appears twice with concrete triggers ("Reach for this skill whenever the task involves editing `<lang>/languageModels/typesystem.mps`"). Matches anchor 5 ("Clearly and explicitly answers both what AND when with concrete trigger phrases"), not 4, because the when-clauses are explicit rather than merely present.

Trigger Term Quality

Contains the natural phrases an MPS user would actually say: "typesystem", "inference rules", "checking rules", "quick-fix", "type stays undefined", "operator cannot be applied", and the file path "`<lang>/languageModels/typesystem.mps`". Matches the anchor "Comprehensive coverage of natural terms including synonyms and file extensions" — user-visible error strings and the `.mps` path are covered, so it exceeds anchor 4's "good keyword coverage; a few natural terms missing".

Distinctiveness Conflict Risk

Occupies a clear niche — the MPS typesystem aspect specifically — and even delineates its boundary against the compiled-typesystem query tools ("For questions to the compiled typesystem (`IS_SUBTYPE`, `EXPLAIN_TYPE`, `GET_EXPECTED_TYPE`), use the query tools"). Matches anchor 5 ("Clear niche with distinct triggers; minimal conflict risk"); sibling MPS aspect skills are disambiguated by the specific rule and statement names.