Roughly 30 lines with no padding or explanation of concepts Claude already knows; the 'driver explains why not what' example earns its place as a concrete quality standard, so every token pulls weight.

Concrete guidance throughout — a precise threshold rule (5% or a fixed floor, whichever greater), exact table columns, named sourcing breakdowns via the internal-gl MCP, and an explicit fallback — which is actionable for an instruction-only skill per the rubric notes.

Clear sequence from inputs to threshold flagging, per-line rows, driver sourcing, and final output, with an explicit escalation checkpoint ('driver unclear — flag for controller') that serves as a validation loop for this batch operation.

A sub-50-line, single-purpose skill with no bundle files and well-organized sections (Threshold, For each flagged line, Sourcing the driver, Output), which scores 3 per the simple-skill guideline.

Lists multiple concrete actions — 'Write flux commentary', 'current vs prior period and vs budget', and 'the driver explained from underlying activity' — going well beyond merely naming the domain, matching the score-3 anchor.

Answers both 'what' (write flux commentary over threshold lines) and 'when' via the explicit 'Use for the month-end close package and management reporting' trigger clause, so it is not capped at 2.

Includes natural domain terms a finance user would actually say — 'flux commentary', 'P&L and balance-sheet', 'month-end close package', and 'management reporting' — with good coverage and no jargon.

A highly specific month-end-close finance niche with distinct triggers, making it unlikely to fire for an unrelated skill.