Conciseness

The body is efficient and assumes competence, with concrete formats and a worked example, but contains minor over-explanation — "This is a fundamental, low-level skill for enabling access" and the trigger pattern repeated across the Trigger Condition, Procedure, and Example sections. This matches anchor 4 (efficient with minor instances that could be trimmed), not anchor 5, since some redundancy could be cut.

Actionability

Guidance is fully executable for this instruction-only skill: the exact output format `Action: open <receptacle_name>`, concrete receptacle names (`fridge 1`, `cabinet 12`, `safe 1`), and a complete worked example (Observation → Thought → Action) that is copy-paste ready. This matches the top anchor; no key details are missing for the common case.

Workflow Clarity

As a simple single-purpose skill with an unambiguous single action and a numbered two-step procedure, it qualifies for the simple-skill exception; the negative guard ("Do not use this skill if the receptacle is already described as open or if its state is not mentioned") further disambiguates. No destructive or batch operation is involved, so the validation cap does not apply.

Progressive Disclosure

The skill is under 50 lines with no need for external references, and the body is organized into clear sections (Trigger Condition, Action, Procedure, Example, Notes) — the rubric explicitly allows a score of 5 for well-organized sections in this case. There are no references to verify and no inlined content that belongs in separate files.

Specificity

The description names the domain and one concrete action ("opens a closed receptacle", "outputs the 'open' action on the specified receptacle"), matching the anchor for 1-2 concrete actions without comprehensive coverage. It is below anchor 4 because only a single action is listed, though the action itself is concrete rather than generic.

Completeness

Both questions are explicitly answered: what ("opens a closed receptacle to allow access to its contents... outputs the 'open' action on the specified receptacle") and when ("It should be triggered when the agent encounters a closed receptacle (e.g., 'The fridge 1 is closed.') that must be opened to proceed"), including concrete trigger phrases. This matches the anchor-5 example structure of what + explicit when with trigger examples.

Trigger Term Quality

It includes natural trigger language such as "closed receptacle", the literal observation pattern "'The fridge 1 is closed.'", "cooling an item with a fridge", and "taking an object from inside a cabinet" — good keyword coverage with concrete phrases. It falls short of anchor 5 because common receptacle variations (drawer, shelf, dishwasher, etc.) are not covered.

Distinctiveness Conflict Risk

The niche is clear and the trigger is distinct (an observation explicitly stating a receptacle "is closed"), so it is mostly distinguishable. Minor overlap risk remains with sibling receptacle skills (take, put, cool, close) that share the same receptacle vocabulary, keeping it below anchor 5.