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core-web-vitals

Optimize Core Web Vitals (LCP, INP, CLS) for better page experience and search ranking. Use when asked to "improve Core Web Vitals", "fix LCP", "reduce CLS", "optimize INP", "page experience optimization", or "fix layout shifts".

64

Quality

77%

Does it follow best practices?

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SecuritybySnyk

Passed

No findings from the security scan

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tessl review fix ./src/resources/skills/core-web-vitals/SKILL.md
SKILL.md
Quality
Evals
Security

Quality

Content

65%

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

A highly actionable, well-structured optimization guide with strong copy-paste code and checklists. Its main gaps are an unlinked reference file, inline-heavy content that overlaps the LCP reference, and an implicit rather than explicit measure→fix→verify workflow.

Suggestions

Link references/LCP.md from the LCP section (e.g., 'See [LCP.md](references/LCP.md) for detailed causes and framework tips') and move the duplicated LCP detail out of SKILL.md to avoid overlap and reduce tokens.

Add an explicit optimization workflow — e.g., '1. Measure baseline with web-vitals/Lighthouse → 2. Identify worst metric → 3. Apply fixes → 4. Re-measure to confirm Good threshold' — with validation checkpoints.

Trim the opening metric definitions ('LCP measures when...', 'INP measures...') that restate concepts Claude already knows, keeping only the threshold table.

DimensionReasoningScore

Conciseness

The body is mostly dense, actionable code with clear ❌/✅ patterns, but it opens by explaining what each metric 'measures' (concepts Claude already knows) and duplicates LCP material that also appears in references/LCP.md, so it could be tightened rather than earning the lean score-3 anchor.

2 / 3

Actionability

It provides fully executable HTML/JS/CSS examples (preload + fetchpriority, chunked yielding, font-display, PerformanceObserver debugging), per-framework snippets, and concrete checklists — copy-paste ready guidance throughout.

3 / 3

Workflow Clarity

Content is organized per metric (common issues → fixes → checklist → debugging) and supplies measurement tools, but there is no explicit numbered measure→fix→re-measure sequence with validation checkpoints; the feedback loop is only implicit, matching the score-2 anchor.

2 / 3

Progressive Disclosure

A bundle file references/LCP.md exists but is never linked or signaled in the body (only external web.dev links appear), and detailed per-metric content that could be split remains inline, fitting the score-2 'references present but not clearly signaled; content that should be separate is inline' anchor.

2 / 3

Total

9

/

12

Passed

Description

90%

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, third-person description with explicit what-and-when structure and excellent natural trigger coverage. Its only weakness is a single generic action verb ('Optimize') rather than a list of concrete capabilities.

DimensionReasoningScore

Specificity

The description names the domain ('Core Web Vitals (LCP, INP, CLS)') and concrete metric targets, but the action is the single verb 'Optimize' rather than multiple distinct concrete actions like extract/fill/merge, so it falls short of the score-3 anchor.

2 / 3

Completeness

It explicitly states what the skill does ('Optimize Core Web Vitals ... for better page experience and search ranking') and provides an explicit 'Use when asked to ...' trigger clause, clearly answering both what and when.

3 / 3

Trigger Term Quality

It lists six natural phrasings a user would actually say — 'improve Core Web Vitals', 'fix LCP', 'reduce CLS', 'optimize INP', 'page experience optimization', 'fix layout shifts' — giving good coverage of common variations.

3 / 3

Distinctiveness Conflict Risk

Core Web Vitals / page-experience optimization is a clear niche with distinct, metric-specific triggers, making it unlikely to fire for an unrelated skill.

3 / 3

Total

11

/

12

Passed

Validation

93%

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

Validation15 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

relative_links

Relative link issues: 1 suspicious

Warning

Total

15

/

16

Passed

Repository
gsd-build/gsd-2
Reviewed

Table of Contents

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