Conciseness

The body is dense and prescriptive — it assumes competence (no explanation of what an API or LLM is) and every section carries non-obvious rules, thresholds, and war stories (Cursor quote-mangling, the git-commit tag injection). It is not score 5 because some narrative explanation (e.g., the four-condition justification in 核心原则 and the multimodal-path comparisons) could be tightened into bare rules, and at ~97 dense lines a few passages over-explain their rationale.

Actionability

For an instruction-only design skill the guidance is copy-paste concrete: exact truncation templates ('已显示第 1-200 行，共 5000 行，可用 offset 继续读取', head 50 + tail 50 lines with a '[省略 8523 行…]' marker), example parameter formats (RFC3339 '2024-03-15T14:30:00Z', E.164 '+8613888888888'), a form-selection decision table, named tool patterns (`read_document(file_type=...)`, `get_page_metadata`, `spawn_subagent`), and concrete run commands (`python cli.py demo`). Specific examples cover the common design cases, matching the score-5 anchor; per the rubric's code_vs_instruction note, the absence of code blocks is not penalized since the guidance is directly actionable.

Workflow Clarity

Mini-workflows are clearly sequenced with explicit checkpoints and error-recovery loops: the execution-safety pipeline '输入验证 → 权限控制 → 提议者-审核者 → Sidecar', the debugging rule 'Agent 频繁选错工具时，先查工具描述', and feedback loops like '审批失败要把拒绝理由…加入轨迹，而不是简单重试' and the Sidecar '拒绝熔断器'. It falls short of score 5 because the skill is a reference guide with no single end-to-end decision procedure (e.g., 'first classify the tool, then apply §X') tying the six practice patterns into one navigable sequence.

Progressive Disclosure

Inline structure is good (clear sections: 何时使用 / 核心原则 / 实践模式 / 常见陷阱 / 配套代码 / 深度阅读), but the bundle contains no files at all — the '配套代码' paths (`chapter4/perception-tools/`, `chapter4/execution-tools/`, `chapter4/collaboration-tools/`, `chapter4/multimodal-agent/`) and '深度阅读' path (`book/chapter4.md`) do not exist in the skill directory, so the references are dangling. This matches the score-3 anchor (references present but not effectively usable / organization could be better) rather than score 4, since navigation to the referenced material is broken.

Specificity

The description enumerates multiple concrete capabilities — '新增/重构工具集、给 MCP 服务器设计工具、判断能力该做成专用工具还是 Skill、编写工具描述与参数 schema、设计感知工具的输出分页与截断、给执行工具加安全审批与沙盒、设计子 Agent 协作接口' — and summarizes scope ('覆盖工具分类、ACI 通用设计原则、感知/执行/协作三类工具的设计要点'). This matches the anchor 'lists multiple specific concrete actions; comprehensive coverage'; it is not score 4 because coverage of the domain is comprehensive rather than having minor gaps.

Completeness

Both halves are explicit: 'when' via the opening use-when clause '设计 Agent 工具时使用——……设计子 Agent 协作接口时查阅' with seven concrete trigger situations, and 'what' via '覆盖工具分类、ACI 通用设计原则、感知/执行/协作三类工具的设计要点'. This clearly matches the score-5 anchor (explicit what AND when with concrete trigger phrases) rather than the score-4 anchor where the 'when' could be more specific.

Trigger Term Quality

Natural trigger phrases users would say are well covered: 'Agent 工具', 'MCP 服务器', '工具描述', '参数 schema', '沙盒', '审批', '分页', '子 Agent'. It falls short of the score-5 anchor because common synonyms such as 'function calling' or 'tool use' (which the body itself uses) are absent from the description, leaving a few natural terms missing.

Distinctiveness Conflict Risk

It occupies a clear niche — designing agent-facing tools (ACI) — with distinctive triggers like '判断能力该做成专用工具还是 Skill' and '设计感知工具的输出分页与截断' that few other skills would claim. Minor overlap with a hypothetical skill-authoring guide exists ('还是 Skill'), but it is small enough that the score-5 anchor ('clear niche with distinct triggers; minimal conflict risk') fits better than score 4.