Conciseness

The body is efficient — each section carries new information (strategic boundaries, script behavior with concrete defaults, hook JSON, env var, best practices) with minimal padding. The 'なぜ戦略的コンパクションか？' rationale section re-states the description's contrast and explains auto-compaction behavior Claude already knows, which keeps it below anchor 5; it is well above anchor 3 because there is no substantial over-explanation.

Actionability

The hook configuration JSON is copy-paste ready, thresholds and defaults are explicit ('COMPACT_THRESHOLD', default 50, reminders every 25), and the plugin-vs-manual install paths are concretely distinguished with an anti-duplication warning. It falls short of anchor 5 because the core script 'suggest-compact.js' and 'install.sh' are referenced but not bundled or shown, leaving a gap in what a user can actually execute from this file alone.

Workflow Clarity

The mechanism is sequenced in three numbered steps (track tool calls, threshold detection, periodic reminders) and the setup path is unambiguous for both install modes, including an explicit warning against double registration. It is a simple config skill with no destructive or batch operation, so no validation checkpoint is required; it misses anchor 5 only because there is no guidance for verifying the hook actually fires after installation.

Progressive Disclosure

The body is a well-organized single file (~60 lines) with clear sections and appropriately short for a standalone SKILL.md; no bundle files exist, so nothing is improperly inlined or deeply nested. It is below anchor 5 because the referenced script and installer are not present in the bundle and the only external pointer is a bare URL to a social-media post rather than a clearly signaled reference document.

Specificity

The description names the domain ('compaction') and one concrete action ('proposes manual compaction at logical intervals to preserve context through task phases'), but lists no further capabilities or configuration hooks. It matches anchor 3 (domain plus 1-2 concrete actions, not comprehensive); it is below anchor 4 because no several specific actions are enumerated, and above anchor 2 because the action stated is concrete, not generic.

Completeness

The 'what' is clearly stated ('proposes manual compaction at logical intervals... rather than arbitrary auto-compaction'), but there is no 'Use when...' clause or equivalent trigger guidance, which per the rubric caps completeness at 3. It is not anchor 4 because 'when' is entirely absent rather than weakly implied, and not anchor 2 because the 'what' is concrete, not vague.

Trigger Term Quality

Relevant domain keywords are present ('自動コンパクション', '手動コンパクション', 'コンテキスト', 'タスクフェーズ') but common user-facing variations are missing — no '/compact', 'context window', 'token limit', or synonyms. Anchor 3 (some relevant keywords, missing common variations) fits best: above anchor 2 because the terms are domain-specific rather than generic, below anchor 4 because key natural trigger phrases are absent.

Distinctiveness Conflict Risk

Compaction-strategy is a narrow niche with few overlapping skills, and the description's contrast with arbitrary auto-compaction distinguishes it further. Anchor 4 (mostly distinct, minor overlap risk with closely related skills) fits: not anchor 5 because no explicit trigger phrases establish the niche, and not anchor 3 because the domain is specific rather than merely 'somewhat specific'.