MCPInstall

21st-ui-review

Review existing UI against the project's design context, accessibility expectations, responsive behavior, interaction quality, and high-confidence production rules. Use for UI audits, design QA, frontend review, accessibility review, consistency checks, or requests to find and safely fix visual defects. Trigger for requests such as "review this UI", "audit this page", "find design issues", "check responsiveness", or "fix obvious UX problems". Use 21st-ui-build when the request is primarily to create new UI.

Installs
1.4K
Last 24h
+25
Trending rank
#4865
Security
Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/21st-dev/skill --skill 21st-ui-review
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads 21st-ui-review automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

Review UI with evidence

Separate deterministic defects from subjective design recommendations.

Workflow

  1. Read .21st/design.json, project instructions, and the relevant source.

  2. Run the deterministic review first:

    21st review <path>
    21st review <path> --json
    
  3. Inspect the actual component composition and runtime states. Validate claims against code rather than inferring behavior from names.

  4. Group findings into:

    • deterministic defects;
    • design-system drift;
    • accessibility and interaction defects;
    • responsive risks;
    • subjective product/design recommendations.
  5. Prioritize by user impact and include exact file and line attribution.

  6. Use 21st review <path> --fix only for deterministic, low-ambiguity fixes. Never silently redesign, change brand identity, or alter product behavior.

  7. Run relevant project tests after fixes and rerun review to prove resolution.

Review priorities

  • semantic controls and accessible names;
  • keyboard access, focus visibility, and dialog/menu behavior;
  • image alternatives and meaningful labels;
  • touch target size and disabled/loading states;
  • responsive overflow and fixed-width assumptions;
  • reduced-motion handling;
  • hardcoded visual values that conflict with project tokens;
  • duplicate primitives instead of existing components;
  • inconsistent typography, radius, spacing, shadows, and icons;
  • fake data, placeholder copy, or missing empty/error states.

Output

Lead with actionable findings ordered by severity. Keep subjective suggestions clearly labeled. If no issue is proven, say so and state what was inspected.

FAQ

What does the 21st-ui-review skill do?

Review existing UI against the project's design context, accessibility expectations, responsive behavior, interaction quality, and high-confidence production rules. Use for UI audits, design QA, frontend review, accessibility review, consistency checks, or requests to find and safely fix visual defects. Trigger for requests such as "review this UI", "audit this page", "find design issues", "check responsiveness", or "fix obvious UX problems". Use 21st-ui-build when the request is primarily to create new UI.

How do I install 21st-ui-review?

Run npx skills add https://github.com/21st-dev/skill --skill 21st-ui-review in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/21st-ui-review/ (personal) or .claude/skills/21st-ui-review/ (project).

Which AI agents can use 21st-ui-review?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is 21st-ui-review safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains 21st-ui-review?

It is published by 21st-dev in 21st-dev/skill. It has 1,370 recorded installs.

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