Conciseness

The body is lean and assumes competence throughout: "Keep adapters thin: parse input, call API/tool, return" is a complete rule in one line, and no section explains concepts Claude already knows. Even the densest part (the Pi exception) carries only binding specifics — endpoint, error codes, timings, status values — with every token earning its place, matching anchor 5 rather than anchor 4's "minor instances that could be trimmed".

Actionability

The guidance is fully implementable without code: it names the exact endpoint ("GET /observations/save-result"), the typed error ("404 with code observation_save_result_not_found"), the timing bound ("cancellable 250 ms backoff"), and the success criteria ("a positive ID and status: \"committed\"" and "legacy positive {id} acknowledgement"). Per the rubric's instruction-only note, the absence of code is not penalized when guidance is this actionable, and the common cases (initial success, ambiguity, typed HTTP errors, caller cancellation) are all covered, so it meets anchor 5 rather than stopping at anchor 4's "minor gaps".

Workflow Clarity

The Pi recovery protocol is a clearly sequenced decision tree with an explicit validation checkpoint ("A lookup confirms success only with a positive ID and status: \"committed\""), but the Compatibility Checklist items ("Claude Code flow still works") state outcomes without any concrete verification method, which is exactly anchor 4's "minor validation gaps". It stays above anchor 3 because the risky recovery flow does have explicit checkpoints and error-recovery branching.

Progressive Disclosure

The body is under 50 lines, needs no external references (none exist in the bundle), and is organized into four clearly delineated sections (When to Use, Boundary Rules, the narrow Pi exception, Compatibility Checklist). The dense Pi exception is a single coherent ~24-line spec that is appropriately inline, so per the simple-skill guideline this matches anchor 5.

Specificity

The description names the domain ("Adapter boundary rules for plugin integrations") but lists no concrete actions — it says what the skill contains, not what it does. Anchor 3 requires 1-2 named actions (cf. "Processes PDF files and extracts content") and none are present; it is above anchor 1 because the domain itself is specifically named rather than pure abstraction.

Completeness

Both halves are present: a "what" ("Adapter boundary rules for plugin integrations") and an explicit "when" ("Trigger: Changes in plugin scripts/hooks for Claude, OpenCode, Pi, Gemini, or Codex"), so the missing-trigger cap of 3 does not apply. It is not anchor 5 because the "what" states no concrete actions or outcomes (e.g., keeping adapters thin, routing logic to the Go core), leaving the capability description thin.

Trigger Term Quality

"Changes in plugin scripts/hooks for Claude, OpenCode, Pi, Gemini, or Codex" gives good natural keyword coverage — users editing agent plugin hooks would plausibly say "plugin", "hooks", "scripts", or one of the five agent names. It falls short of anchor 5's comprehensive synonym coverage (e.g., "adapters", "memory capture", "agent integrations" are absent as trigger phrases), but clearly exceeds anchor 3 because the main variations are covered via the agent names.

Distinctiveness Conflict Risk

The trigger is narrowed by five named agents and the specific artifacts "plugin scripts/hooks", giving a clear niche with minor overlap risk against generic plugin-authoring guidance. Not anchor 5: "plugin integrations" in the first sentence is still broad enough to collide with general plugin-development skills.