Conciseness

Most of the body is genuinely non-obvious domain data (per-market cost tables, impact coefficients, the model-selection tree) that earns its tokens, but it opens with a motivational 'Why Slippage Models Are Needed' block explaining basics Claude already knows ('the order book has a bid-ask spread', 'large orders push prices'), and repeats the commission=0.001 recommendation in three separate sections. It fits 'mostly efficient but includes some unnecessary explanation or could be tightened' rather than level 4's 'minor instances'.

Actionability

The skill provides mostly executable guidance: complete Python functions (fixed_slippage, linear_impact, sqrt_impact) with documented arguments, concrete parameter ranges in tables, a capital-vs-ADV decision tree, and explicit config examples. It falls short of fully copy-paste-ready (level 5) because delayed_execution uses pd.Series without importing pandas, and the SignalEngine.generate snippet references an undefined signals dict and self._compute_signal, so it will not run as written.

Workflow Clarity

There are sequenced processes — the three-step cost-impact analysis framework and the slippage-model selection decision tree — but no validation checkpoints or feedback loops anywhere (e.g. 'verify the fill assumptions against historical VWAP before accepting results'). The sequence is present but checkpoints are missing or only implicit, matching the level-3 anchor.

Progressive Disclosure

The body has clear section structure but is a ~340-line monolithic document with no bundle files at all: per-market reference tables, the cost-coefficient data, and the code snippets are exactly the material that belongs in references/ files linked one level deep. It matches 'some structure but content that should be separate is inline' — better than the unstructured level-2 anchor, but with no reference architecture to reach level 4.

Specificity

The description enumerates multiple concrete, domain-specific actions — 'slippage formulas (linear / square-root impact)', 'VWAP/TWAP execution logic', 'market-impact cost estimation', and 'execution-assumption configuration' — giving comprehensive coverage of the skill's capabilities with no padding or buzzwords. It clearly exceeds the level-4 anchor ('several specific actions; minor gaps') because every named capability maps to a real section of the skill.

Completeness

The 'what' is clear and specific (trade execution modeling for backtests with named sub-capabilities), but there is no 'Use when...' clause or equivalent explicit trigger guidance — '(backtest only)' is a scope qualifier, not a usage trigger. Per the judging guidelines, a missing 'when' clause caps completeness at 3.

Trigger Term Quality

It contains good, natural trigger terms practitioners would actually say — 'slippage', 'VWAP', 'TWAP', 'market impact', 'backtest', 'execution' — but misses common variations like 'transaction costs', 'fill price', or 'order execution'. It fits the level-4 anchor ('good keyword coverage; a few natural terms missing') rather than level 5, which requires synonym- and extension-level coverage.

Distinctiveness Conflict Risk

'Trade execution modeling (backtest only)' with VWAP/TWAP and slippage jargon carves out a clear niche that is unlikely to fire for unrelated skills. It falls short of level 5 because it could still overlap with a broader 'backtesting configuration' or 'transaction cost analysis' skill sharing terms like 'backtest' and 'execution'.