vercel-react-best-practices
React and Next.js performance optimization guidelines from Vercel Engineering. This skill should be used when writing, reviewing, or refactoring React/Next.js code to ensure optimal performance patterns. Triggers on tasks involving React components, Next.js pages, data fetching, bundle optimization, or performance improvements.
68
62%
Does it follow best practices?
Impact
66%
1.15xAverage score across 3 eval scenarios
Passed
No known issues
Optimize this skill with Tessl
npx tessl skill review --optimize ./skills/vercel-react-best-practices/SKILL.mdQuality
Discovery
82%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
This is a solid description that clearly communicates its purpose and includes explicit trigger guidance. Its main weakness is that it describes the domain at a high level without listing specific concrete optimization techniques, and its triggers are broad enough that it could conflict with general React/Next.js development skills. Adding specific actions would strengthen both specificity and distinctiveness.
Suggestions
Add specific concrete actions like 'Implements code splitting, lazy loading, image optimization, memoization, server component patterns, and caching strategies' to improve specificity.
Narrow the trigger conditions to reduce conflict risk—e.g., specify 'Use when the user mentions slow rendering, large bundle size, Core Web Vitals, or asks to optimize React/Next.js code' rather than broadly triggering on any React component work.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Names the domain (React/Next.js performance optimization) and mentions some areas like 'data fetching, bundle optimization, performance improvements,' but doesn't list specific concrete actions (e.g., 'lazy load components, optimize images, implement code splitting, configure caching headers'). | 2 / 3 |
Completeness | Clearly answers both 'what' (React and Next.js performance optimization guidelines) and 'when' (writing/reviewing/refactoring React/Next.js code, with explicit triggers on components, pages, data fetching, bundle optimization, performance improvements). | 3 / 3 |
Trigger Term Quality | Includes strong natural keywords users would say: 'React', 'Next.js', 'performance', 'React components', 'Next.js pages', 'data fetching', 'bundle optimization', 'refactoring'. These cover common terms a developer would use when seeking performance help. | 3 / 3 |
Distinctiveness Conflict Risk | While it's specific to React/Next.js performance, it could overlap with general React coding skills, Next.js development skills, or broader web performance optimization skills. The 'React components' and 'Next.js pages' triggers are quite broad and could fire for non-performance-related React/Next.js tasks. | 2 / 3 |
Total | 10 / 12 Passed |
Implementation
42%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This skill functions well as a navigational index with good progressive disclosure and clear categorization by priority, but it lacks actionability—there are zero concrete code examples or executable patterns in the body itself. The content essentially serves as a table of contents, deferring all substantive guidance to external files, which means Claude gains very little actionable knowledge from the skill body alone.
Suggestions
Add at least one concrete, executable code example per critical category (e.g., show a before/after for async-parallel with Promise.all(), or bundle-barrel-imports with direct import paths) so the skill body provides immediate value.
Include a brief workflow section describing how to apply these rules during code review or refactoring, e.g., '1. Check for waterfalls → 2. Audit bundle imports → 3. Verify with Lighthouse/bundle analyzer'.
Remove the 'When to Apply' section—Claude can infer when React/Next.js performance guidelines are relevant from context.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The content is mostly efficient as a reference index, but the 'When to Apply' section and the introductory paragraph explain things Claude can infer. The table of 45 rules with prefixes is useful but the brief descriptions add minimal value without the actual rule content—they're essentially just slightly expanded names. | 2 / 3 |
Actionability | The skill provides no executable code, no concrete examples, and no specific patterns to follow. It's entirely a catalog/index of rule names with one-line descriptions. All actual guidance is deferred to external files (rules/*.md, AGENTS.md), making this skill body essentially a table of contents with no actionable content on its own. | 1 / 3 |
Workflow Clarity | The priority ordering provides a clear sequence for which optimizations to tackle first, and the categorization is well-structured. However, there are no validation steps, no workflow for applying these rules during code review or refactoring, and no guidance on how to verify improvements. | 2 / 3 |
Progressive Disclosure | The skill is well-structured as an overview with clear references to individual rule files (rules/async-parallel.md, etc.) and a compiled document (AGENTS.md). Navigation is one level deep and clearly signaled, with each rule file's expected contents described. | 3 / 3 |
Total | 8 / 12 Passed |
Validation
100%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 11 / 11 Passed
Validation for skill structure
No warnings or errors.
- Repository
- am-will/codex-skills
- Commit
ca2c3b3
- Reviewed
Table of Contents
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