Conciseness

The body is densely packed — nearly every line carries a non-obvious heuristic, formula, or quantified example ("Pass@k = 1-(1-p)^k", "100 个用例、成功率 70% 时 95% 置信区间约 ±9 个百分点", "28.3% 与 17.5% 合用只有 30%"), with no padding. It is not a 5 because a few passages explain concepts Claude already knows (the prefill/decode latency model, the Goodhart's-law gloss, McNemar testing), which could be trimmed.

Actionability

For an instruction-only skill the guidance is largely concrete: a structured attribution record with named fields (任务名、首错步号、错误类别、责任方、原文证据、置信度), a named three-rule pre-filter for suspect trajectories, the trajectory-prefix bisection procedure, and specific operational parameters ("每个配置跑 3–5 个随机种子"). It falls short of fully executable because there is no copy-paste-ready code or command, and several items remain at the level of principles ("看 p95 尾部延迟而非均值").

Workflow Clarity

Several sections present clear sequences with explicit validation gates and feedback loops — section 10's "小范围通过只获得扩大测试的资格：标准环境、全任务 × 多种子…完整复测通过前不部署" and the hypothesis-chain loop; section 5 defines acceptable-action sets rather than single answers. Not a 5 because the skill aggregates ten parallel practice areas rather than one coherent end-to-end workflow, and entry-point sequencing across them is implicit.

Progressive Disclosure

The single SKILL.md inlines all ~110 lines of dense practice detail (content that, given the topic breadth, plausibly belongs in separate reference files), and every path it points to — "chapter7/tau2-bench-eval/", "chapter7/agent-cost-analysis/", "book/chapter7.md" — does not exist in the bundle, so the 配套代码/深度阅读 sections lead nowhere. Sections and reference labels are clear, placing this above anchor 2, but the dangling references and inline bulk keep it below the well-organized, working-references level of anchor 4.

Specificity

The description enumerates ten-plus concrete actions — "设计评估指标（Pass@k/Pass^k/成本）", "搭建可重复运行的评估环境", "选择确定性验证器或 LLM-as-a-Judge 及各自适用边界", "编写 Rubric", "做失败归因与回归任务", "判断统计显著性", "建设可观测性与内部评估基础设施（消融、AB 测试、特性开关、提示词回归）" — matching the anchor for multiple specific concrete actions with comprehensive coverage. Score 4 would require minor gaps in coverage, but the action list spans the skill's full surface.

Completeness

Explicitly answers both questions: the leading clause "为 Agent 建立或改进评估体系时使用" is a concrete 'when', and the long action list is a clear 'what'. This matches the anchor for clearly and explicitly answering both with concrete trigger phrases.

Trigger Term Quality

Natural trigger terms are present — "评估体系", "评估指标", "Rubric", "失败归因", "统计显著性", "AB 测试", "Benchmark 报告" — giving good keyword coverage. Missing a few natural synonyms and variations users would say ("评测", "测试集/评估集", "回归测试"), so it sits between anchor 4 and 5, closer to 4.

Distinctiveness Conflict Risk

The niche is unambiguous — building/improving evaluation systems for Agents — and distinctive terms (Pass^k, LLM-as-a-Judge 及适用边界, 失败归因) give it minimal overlap with generic testing or infrastructure skills. Only "AB 测试"/"特性开关" lightly touch adjacent infra topics, which is not enough to drop below the clear-niche anchor.