The body is lean and assumes Claude's competence: Problem/Solution framing with tight numbered steps and specific thresholds, e.g. 'Identify outputs exceeding 50 lines or 1 KB' and 'Trigger compaction every 10 turns or 8k tokens', without explaining concepts Claude already knows. It is not a 2 because there is no padding or unnecessary explanation; minor reference redundancy is not enough to drop it.

Concrete thresholds and explicit keep/drop lists ('Keep: User Goal, Active Task, Current Errors, Key Decisions') and ordering ('System -> Tools -> RAG -> User') are actionable, but the core masking mechanism is abstract in-body ('replace raw data with summary placeholder') with execution details delegated to references. It is not a 3 because the key 'how' of masking/rewriting history is incomplete in the body, and not a 1 because the guidance is specific and instructive.

Sections 1 and 2 present clear numbered sequences (Identify -> Extract -> Mask; Trigger -> Compact -> Format), but there are no validation checkpoints or feedback loops, and masking/compaction are destructive history-rewriting operations. Per the rubric, missing validation for destructive operations caps this at 2; it is not a 1 because sequences are clearly listed.

The body is an overview pointing to well-signaled one-level-deep references ([references/masking.md], [references/compaction.md], [references/implementation.md]); the bundle files exist and are self-contained with no further nesting. Content is appropriately split (overview in body, patterns/algorithms/examples in references). It is not a 2 because navigation is clear and references are not deeply nested.

Lists multiple concrete actions in third person: 'Maximize context window efficiency, reduce latency, and prevent lost-in-middle issues through strategic masking and compaction.' These name specific techniques (masking, compaction) rather than vague abstraction, matching the multiple-concrete-actions anchor; it is not a 2 because it goes beyond naming a domain and a couple of actions.

Clearly answers both what ('Maximize context window efficiency... through strategic masking and compaction') and when via an explicit 'Use when token budgets are tight, tool outputs overflow the context, conversations drift from intent, or latency spikes from cache misses' clause. It is not a 2 because the 'when' is explicit rather than implied.

The 'Use when' clause offers some natural triggers ('token budgets are tight', 'tool outputs overflow the context', 'conversations drift from intent'), but leans on technical jargon like 'lost-in-middle issues' and 'cache misses' that users would not naturally say, missing common variations. It is not a 3 because the keyword set is not consistently natural, and not a 1 because several phrases are usable triggers.

The context-window-optimization niche is fairly specific, but triggers like 'summarize history' and 'conversations drift from intent' overlap with general summarization/compaction skills, so it could still trigger for the wrong skill. It is not a 3 because the niche is not cleanly separated from adjacent skills, and not a 1 because it is not generically broad.