The body is lean and assumes Claude's competence — it conveys dense domain knowledge (pre-attach timing, sampleNode narrowing, SPropertyAccess vs SLinkAccess) without padding or explaining concepts Claude already knows.

Gives concrete MCP tool calls (`mps_mcp_insert_root_node_from_json`, `mps_mcp_update_node`, `mps_mcp_check_root_node_problems`, `mps_mcp_parse_java_and_insert` with `featureKind: "STATEMENTS"`), exact model-naming rules, and a runnable setup-body pattern, with copy-paste JSON routed to real blueprint references.

A numbered Common-Path Workflow (steps 1–5) ends in an explicit validation checkpoint — `mps_mcp_check_root_node_problems`, rebuild, sandbox — and the Critical Directives reinforce validate-after-edit for this risky language-model editing.

A Reference Index signals exactly when to open each one-level-deep reference (node-factories-and-triggers, setup-function-bodies, json-blueprints, copy-paste-and-paste-wrappers, concept-reference, common-failures), all of which are real files in ./references/.

Lists multiple concrete actions: defining/editing `NodeFactories` roots, per-concept `NodeFactory` setup functions that initialize a fresh node and copy from `sampleNode`, plus `CopyPasteHandlers` and `PasteWrappers` roots.

Explicitly answers both what (node factories, setup functions, copy/paste handlers) and when ("Use when...", "Reach for this skill when...") with explicit trigger guidance.

Surfaces natural MPS trigger phrases a user would say — "substitution", "side transform", "completion replacement", "add new initialized(...)", "preserve fields from the node it is replacing", and "defaults set in a constructor are not enough".

A clear niche — the MPS actions aspect and factory sampleNode carry-over — distinct from sibling aspects, even carving constructor-vs-factory boundaries, so it is unlikely to trigger the wrong skill.