The body is dense and operational with no padding — it never explains what MPS or a constraint is, and lines like 'Setter (propertySetter) — normalises and must explicitly assign node.<prop> = propertyValue' assume Claude's competence; every token carries domain-specific knowledge Claude does not already have, matching the 'lean and efficient; every token earns its place' anchor rather than the score-2 'includes some unnecessary explanation'.

It gives concrete, executable guidance — specific MCP tool calls with parameters (mps_mcp_insert_root_node_from_json, mps_mcp_check_root_node_problems, mps_mcp_parse_java_and_insert), exact model imports (jetbrains.mps.lang.constraints, jetbrains.mps.scope), and named concept roots (ConceptConstraints, NodePropertyConstraint); per the code-vs-instruction note, deferring full JSON/code blueprints to reference files is not penalized since the in-body guidance is concrete and actionable, clearing the 'fully executable code/commands; specific examples' anchor.

The 'Common-Path Workflow' is a clearly sequenced 6-step process with an explicit validation checkpoint (step 6: 'Validate with mps_mcp_check_root_node_problems and rebuild the language') and a feedback loop for error recovery ('if the new constraint is invisible at runtime, run mps_mcp_reload_all'), matching the 'clear sequence with explicit validation steps; feedback loops for error recovery' anchor rather than the score-2 'validation gaps; checkpoints missing'.

The body is a focused overview with a 'Reference Index' that gives 'Open references/X.md when ...' guidance for each of seven one-level-deep reference files (all verified present — referent-constraints.md is ~46KB, scope-fqn-reference.md ~13KB, confirming heavy detail was correctly externalized); navigation is well-signaled and content appropriately split, matching the 'clear overview with well-signaled one-level-deep references' anchor.

Lists many concrete capabilities — 'property validators / setters / getters, referent search scopes (imperative or inherited via ScopeProvider.getScope), referentSetHandler side effects, default-scope blocks, canBeChild / canBeParent / canBeAncestor / canBeRoot placement rules, defaultConcreteConcept ... set <read-only> and {name} aliasing, and scope helpers (SimpleRoleScope, ListScope, CompositeScope, HidingByNameScope)' — matching the 'lists multiple specific concrete actions' anchor, not the score-2 'names domain and some actions' level.

Explicitly answers both 'what' (the enumerated capability areas) and 'when' via two explicit triggers — 'Use when defining or editing MPS language constraints' and 'Reach for this skill whenever the task involves authoring or modifying <lang>/languageModels/constraints.mps' — satisfying the score-3 'clearly answers both what AND when with explicit triggers' anchor rather than the score-2 'when is missing or only implied'.

Opens with the natural trigger 'Use when defining or editing MPS language constraints' and covers the capability terms an MPS user would actually say (validators, setters, getters, referent search scopes, placement rules, scope helpers); the backticked API symbols add specificity rather than displacing natural phrasings, so it clears the 'good coverage of natural terms' anchor over the score-2 'some relevant keywords but missing common variations'.

A sharply bounded niche — the MPS constraints aspect, a concrete file path (constraints.mps), and distinctive API names (ScopeProvider.getScope, canBeChild, defaultConcreteConcept) — make it unlikely to fire for any other skill, matching the 'clear niche with distinct triggers; unlikely to conflict' anchor rather than the score-2 'could still overlap with similar skills'.