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performance-testing

Performance testing with Lighthouse and Web Vitals integration in Playwright. Use when measuring page load times, Core Web Vitals, Lighthouse audits, or performance budgets.

Quality

82%

Does it follow best practices?

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SKILL.md
Quality
Evals
Security

Quality

Content

71%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A code-rich, largely executable skill document with well-organized sections and assertion-based checkpoints, but it functions as a monolithic reference rather than an overview: nearly 500 lines inlined, one dangling reference (references/lighthouse-config.md does not exist), and a few code examples with small assembly gaps (unresolved 'web-vitals' import in addInitScript, missing `fs` import, missing package in install command).

Suggestions

Fix the broken reference: either create references/lighthouse-config.md or remove it from the References section, since the body currently points to a file that does not exist in the bundle.

Split bulk detail out of SKILL.md into one-level-deep reference files (e.g., move the mobile/desktop Lighthouse configs, Performance Timing API, budget definitions, and CI GitHub Actions YAML into references/), keeping SKILL.md to quick start, installation, and pointers.

Tighten code assembly gaps: import `fs` in the metrics-tracking example, use a CDN/bundled build for the web-vitals library in addInitScript (or document the setup), and add `web-vitals` to the npm install command.

DimensionReasoningScore

Conciseness

The body is code-dominant with almost no concept explanation (no 'what is Lighthouse' padding), and comments in code carry threshold knowledge compactly ("// Good LCP < 2.5s"), matching the 'efficient; minor instances of over-explanation that could be trimmed' anchor. It is not a 5 because the Quick Start largely duplicates the 'Basic Audit' example, several samples can only be assembled by combining snippets across sections (e.g., `fs` is imported in one example but used in a later one), and the ~490-line bulk exceeds what a SKILL.md overview needs. It is well above a 3 since there is no real concept teaching, just minor tightening opportunities.

4 / 5

Actionability

Nearly all guidance is complete, executable TypeScript/YAML (playAudit calls with thresholds, PerformanceObserver snippets, CDP throttling commands, a GitHub Actions workflow), matching the 'mostly executable guidance; concrete code with minor gaps' anchor. It is not a 5 because of small execution gaps: the 'web vitals with library' example injects an ES-module `import ... from 'web-vitals'` via addInitScript content that won't resolve in the page without bundling/CDN setup, `fs` is used in the metrics-tracking example without a local import, and the web-vitals npm package is never added to the installation command. It clearly exceeds a 3 because the examples are real code, not pseudocode, and cover the common cases.

4 / 5

Workflow Clarity

Each section is a self-contained, sequenced pattern (navigate -> measure -> assert), and the expect() assertions act as explicit checkpoints, matching the 'clear sequence with most checkpoints present; minor validation gaps' anchor. It is not a 5 because there is no guidance for flakiness handling in a domain where run-to-run variance is the core hazard (the Best Practices bullet 'Cache and repeat - Run multiple times for consistency' is a one-line hint with no concrete retry/median procedure), and there is no decision guidance for when to use Lighthouse vs raw PerformanceObserver. It is above a 3 because assertions/checkpoints are consistently present, not implicit.

4 / 5

Progressive Disclosure

Per the bundle-aware guideline, scoring against the actual bundle: the body cites two reference files but only `references/web-vitals-guide.md` exists; `references/lighthouse-config.md` is a dangling reference. Additionally, ~490 lines of detailed presets (mobile/desktop Lighthouse configs, Navigation/Resource Timing, budget tables, CI YAML) are inlined in SKILL.md when they clearly belong in reference files, matching the 'some structure but could be better organized; content that should be separate is inline' anchor. It is not a 4 because of the broken reference and the monolithic bulk; it is above a 2 because sections are well-organized and the reference list at the end is clearly signaled rather than buried.

3 / 5

Total

15

/

20

Passed

Description

87%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong description: third-person, concise, tool-specific, with an explicit 'Use when' clause covering concrete natural-language triggers. Minor room to broaden trigger synonyms (e.g., 'page speed', 'slow page') and to hint at throttling/reporting capabilities, but nothing vague or over-claimed.

DimensionReasoningScore

Specificity

The description names the domain and tools concretely ("Performance testing with Lighthouse and Web Vitals integration in Playwright") and lists several specific actions/objects ("measuring page load times, Core Web Vitals, Lighthouse audits, or performance budgets"), matching the 'several specific actions; minor gaps' anchor. It falls short of a 5 because the actions are all framed around measuring/auditing and don't cover adjacent capabilities shown in the body (e.g., network/CPU throttling, report generation), and it sits above a 3 because more than 1-2 concrete actions are explicitly named.

4 / 5

Completeness

It explicitly answers 'what' ("Performance testing with Lighthouse and Web Vitals integration in Playwright") and 'when' with a concrete "Use when..." clause listing four trigger phrases, matching the 5 anchor that requires both what and when with concrete trigger phrases. It is not a 4 because the 'when' is already explicit and specific rather than merely present-but-could-be-more-specific.

5 / 5

Trigger Term Quality

Natural user phrases like "page load times", "Core Web Vitals", "Lighthouse audits", and "performance budgets" give good keyword coverage, matching the 'good keyword coverage; a few natural terms missing' anchor. It misses common variations a user might say (e.g., "site speed", "page speed", "LCP/CLS", "slow page"), so it does not reach the comprehensive-synonym coverage of a 5; it clearly exceeds the 'some relevant keywords but missing common variations' level of a 3.

4 / 5

Distinctiveness Conflict Risk

The combination of Lighthouse, Web Vitals, and Playwright plus budget/audit triggers carves out a clear niche with minimal overlap risk against generic testing or general web skills, matching the 'clear niche with distinct triggers; minimal conflict risk' anchor. It is above a 4 because the trigger terms are tool-specific enough that it would not fire for adjacent skills (e.g., unit testing or generic Playwright helper skills without a performance angle).

5 / 5

Total

18

/

20

Passed

Validation

87%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 14 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

frontmatter_unknown_keys

Unknown frontmatter key(s) found; consider removing or moving to metadata

Warning

referenced_paths_exist

Referenced path issues: 1 missing

Warning

Total

14

/

16

Passed

Repository

fernandezbaptiste/Skrillz

Path

skills/performance-testing/SKILL.md

Reviewed

Table of Contents

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