design-performance-critic

design-performance-critic is an agent for Claude Code from Claude-Code-Community-Ireland/claude-code-resources. It costs 48 tokens per session (2,934 once invoked), scanned A, original, MIT.

An agent that checks the performance of a web interface by examining its CSS, assets, loading approach, and runtime behavior.

In plain words
What is it for?
Use it to audit HTML and CSS designs, assess asset optimization and loading strategies, and produce performance reports.
Why use it?
It helps reveal design choices that could make a page slower, such as inefficient styles, unoptimized files, or poor loading decisions.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the vibeworks-library plugin — 34 skills, 21 commands, 33 agents, 3 hooks shipped together

Good fit Use it to audit HTML and CSS designs, assess asset optimization and loading strategies, and produce performance reports.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/claude-code-community-ireland/claude-code-resources/design-performance-critic
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/claude-code-community-ireland/claude-code-resources/design-performance-critic
Clone the repo
git clone --depth 1 https://github.com/Claude-Code-Community-Ireland/claude-code-resources

Made for: Claude Code.

Or install vibeworks-library, the plugin that ships this one along with the rest of its 34 skills, 21 commands, 33 agents, 3 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for design-performance-critic

README.md
[![agentmods](https://agentmods.dev/badge/agents/claude-code-community-ireland/claude-code-resources/design-performance-critic.svg)](https://agentmods.dev/agents/claude-code-community-ireland/claude-code-resources/design-performance-critic)
Your own site
<a href="https://agentmods.dev/agents/claude-code-community-ireland/claude-code-resources/design-performance-critic"><img src="https://agentmods.dev/badge/agents/claude-code-community-ireland/claude-code-resources/design-performance-critic.svg" alt="Measured on agentmods" height="20"></a>
Per session 48 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,934 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00048 $0.02934
Opus 5 $0.00024 $0.01467
Sonnet 5 $0.00010 $0.00587
Haiku 4.5 $0.00005 $0.00293

Measured 6d ago against content hash df0db818a4e8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

design-performance-critic scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/vibeworks-library/agents/design-performance-critic.md · 458 lines

How it starts

The opening of the file, as written. The whole thing — 458 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Performance Critic

You evaluate the performance characteristics of generated designs, focusing on CSS efficiency, asset optimization, loading strategies, and best practices for fast-loading pages.

You are a self-improving agent. Before signaling completion, you MUST run your internal Ralph Wiggum Loop to ensure audit quality meets your internal standards.

Self-Improvement Architecture

This agent implements an internal Ralph Wiggum Loop for autonomous quality refinement.

Internal Quality Gates

Gate Threshold Weight Description
css_analysis 0.90 0.40 CSS efficiency evaluated
asset_analysis 0.85 0.30 Asset optimization checked
loading_analysis 0.85 0.30 Loading performance assessed

Phase 1: Execute

Perform performance audit of the design.

Input:

  • Design files (HTML, CSS)
  • Design brief context
  • Previous iteration feedback (if any)

Output:

  • CSS efficiency report
  • Asset optimization assessment
  • Loading strategy evaluation
  • Runtime performance analysis

Execute with haiku model for focused analysis.

Phase 2: Evaluate

Self-critique your audit output against the internal quality gates.

Evaluation Checklist:

css_analysis (weight: 0.40)
  • Is CSS file size measured?
  • Are selector complexity issues identified?
  • Are unused styles detected?
  • Are CSS custom properties used efficiently?
  • Are media queries organized?
asset_analysis (weight: 0.30)
  • Are all images inventoried?
  • Are image formats appropriate (WebP, SVG)?
  • Are image dimensions specified?
  • Is lazy loading implemented?
  • Is font loading optimized?
loading_analysis (weight: 0.30)
  • Is critical CSS identified?
  • Are render-blocking resources noted?
  • Is resource prioritization assessed?
  • Are Core Web Vitals predictions reasonable?
  • Are async/defer attributes used appropriately?

Scoring:

score = (css_analysis × 0.40) + (asset_analysis × 0.30) + (loading_analysis × 0.30)

Read the full file on GitHub · 458 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 458 lines · 48 tokens per session scan A df0db818a4e8

Subscribe to this mod's changes

design-performance-critic is an agent published in the GitHub repository Claude-Code-Community-Ireland/claude-code-resources (10 stars, last pushed 3mo ago), licensed MIT. It adds 48 tokens to every session and 2,934 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other agents, from other repositories

a11y-auditor

Accessibility audit of UI — keyboard navigation, focus-visible, APCA contrast, ARIA roles and labels, touch targets, and reduced-motion. Use to audit a diff, file, or surface for accessibility issues.

educlopez/ui-craft · 49 tokens

ui-developer

Build and refactor UI components in the project's frontend stack — typed props, design-token consistency, accessibility as a gate, and state handling for loading, error, and empty.

atretyak1985/swarmery · 39 tokens

wireframe-reviewer

Reviews wireframe HTML files and UI designs using dual-persona evaluation (efficiency + delight). Scores out of 100 with actionable feedback. Use when: reviewing a wireframe, evaluating a UI design, scoring a prototype, auditing a generated HTML page for design quality, or comparing design options. Uses Read, Glob…

kumaran-is/claude-code-onboarding · 77 tokens

ui-developer

Use this agent when you need to implement or fix UI components based on design references or designer feedback. This agent is a senior UI/UX developer specializing in pixel-perfect implementation with React, TypeScript, and Tailwind CSS. Trigger this agent in these scenarios:\n\n \nContext: Designer has reviewed…

MadAppGang/claude-code · 338 tokens

amadeus-design-agent

UX/UI designer responsible for wireframing, interaction design, accessibility, and design system compliance. Leads Rough Mockups and Refined Mockups stages. Supports User Stories and Application Design.

amadeus-dlc/amadeus · 43 tokens

gem-designer

UI/UX design specialist — layouts, themes, color schemes, design systems, accessibility.

KIMISKI33/awesome-copilot · 22 tokens