Conciseness

The body is mostly efficient (command example, compact input table, troubleshooting in two lines), but includes content that could be tightened: the intro paragraph restates the description almost verbatim ("Save a prefab. Use it when you are in prefab editing mode... Use 'assets-prefab-open' tool to open a prefab first"), and ~45 lines of generic AssetObjectRef/$defs boilerplate descriptions ("Reference to UnityEngine.Object asset instance. It could be Material, ScriptableObject, Prefab...") are duplicated padding for a single-tool doc. This matches 'mostly efficient but includes some unnecessary explanation or could be tightened' rather than the minor-trimming of anchor 4, but is far from the concept-explaining verbosity of anchor 1-2.

Actionability

Provides a concrete, executable CLI invocation ("unity-mcp-cli run-tool assets-prefab-save --input '{...}'"), complete input and output JSON schemas, and actionable troubleshooting ("npm install -g unity-mcp-cli" / "npx unity-mcp-cli"). It falls short of fully copy-paste-ready (anchor 5) because the primary example uses a placeholder payload ("nothing": "string_value") and the stdin variant shows generic {"param": "value"} rather than a realistic invocation — minor gaps consistent with anchor 4.

Workflow Clarity

For a simple single-action skill the sequence is unambiguous: it states the precondition ("Use it when you are in prefab editing mode", "Use 'assets-prefab-open' tool to open a prefab first") and an explicit failure checkpoint ("Throws when no prefab stage is currently open"), with the returned AssetObjectRef serving as the success signal. It is not score 5 because there is no guidance on what to do after the call (e.g. verifying the returned asset path or handling the throw), a minor validation gap matching anchor 4; the destructive/batch cap does not apply since this is a single user-requested save, not a batch operation.

Progressive Disclosure

Well-organized single-file tool doc with clear sections (Behavior, How to Call, Troubleshooting, Input, Output) and no nested or buried references; the one cross-skill pointer ("Read the /unity-initial-setup skill") is clearly signaled. It is not score 5 because the ~50-line output schema block with generic type definitions is inline content that arguably belongs in a shared reference, and the body runs ~100 lines rather than the lean overview the under-50-line exception rewards — minor organization gaps consistent with anchor 4.

Specificity

"Save the currently opened prefab edit stage back to its prefab asset without exiting the stage" is a precise, concrete action in a named domain (Unity prefab assets), plus a second concrete behavior ("Pair with 'assets-prefab-open' to enter the edit mode first") — 1-2 concrete actions, matching the anchor for a domain with 1-2 actions rather than 'several specific actions' (score 4). It is well above the generic 'Names the domain but actions are minimal' anchor (score 2) because the action is described with distinguishing specifics ("without exiting the stage").

Completeness

The 'what' is clearly and explicitly stated (save the open prefab stage back to its asset without exiting), but there is no 'Use when...' clause or equivalent explicit trigger guidance — the closest is "Pair with 'assets-prefab-open' to enter the edit mode first", which is a precondition/pairing note rather than explicit trigger guidance. Per the judging guideline, a missing 'Use when' clause caps completeness at 3 even though the 'what' is clear; it is not score 2 because 'what' is neither vague nor missing.

Trigger Term Quality

Contains the core natural terms a Unity user would say — "prefab", "prefab asset", "save", "edit stage", "edit mode" — which is good keyword coverage. It falls short of anchor 5 (comprehensive synonyms/extensions, e.g. "prefab mode", "apply prefab changes", "Unity", ".prefab") but clearly exceeds anchor 3 ("Works with PDF files"-level minimal coverage) because multiple natural phrasings are present.

Distinctiveness Conflict Risk

It carves a clear niche (saving a prefab while still in its edit stage) and explicitly disambiguates from its closest sibling ("Pair with 'assets-prefab-open' to enter the edit mode first", "without exiting the stage"), giving minimal conflict risk within the prefab tool family. It is not score 5 because a user asking generically to 'save a prefab' (e.g. saving an asset outside a stage) could still trigger it, a minor overlap with closely related skills.