The body assumes Claude's competence — no filler explaining what an LLM proxy or Python file is — and every section (exports table, primitives, patterns, checklist) earns its place with executable code, matching the score-3 lean-and-efficient anchor.

Provides copy-paste-ready, executable code for module structure, the chat/llm/config/selection primitives with real method signatures, and concrete common patterns, plus explicit file paths, matching the score-3 anchor for fully executable guidance.

A clear 'Before You Write Code' sequence and a final verification Checklist give an explicit build sequence with end-state checkpoints; this is a generative (non-destructive) skill so the destructive-validation cap does not apply, matching the score-3 anchor.

A single self-contained SKILL.md with well-signaled, one-level-deep section headers and no nested reference chains; external doc paths are explicitly named and the structure is cleanly navigable, matching the score-3 anchor for a well-organized overview.

Lists multiple concrete actions — 'build a Boost module', 'write a custom module', 'add a new feature to the Boost proxy pipeline', and 'middleware that transforms, augments, or intercepts LLM chat completions' — matching the score-3 anchor of multiple specific concrete actions.

Explicitly states both what (create Harbor Boost modules / Python plugins in Harbor's LLM proxy) and when ('Use this skill whenever the user wants to build a Boost module...' plus 'Also triggers when...'), matching the score-3 anchor for both what and when with explicit triggers.

Includes natural phrasings a user would actually say — 'boost module', 'boost plugin', 'custom module for boost' — giving good coverage of common variations, matching the score-3 anchor.

Tied to a clearly specific niche (Harbor Boost modules, a particular LLM proxy with an ID_PREFIX model-prefix mechanism) that is unlikely to conflict with generic coding skills, matching the score-3 anchor of a clear niche with distinct triggers.