Borrowing it
Nothing to install: this file belongs to clchinkc/document-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/clchinkc/document-mcp/main/.claude/agents/frontend-system-builder.mdgit clone --depth 1 https://github.com/clchinkc/document-mcpWrote 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.
[](https://agentmods.dev/agents/clchinkc/document-mcp/frontend-system-builder)<a href="https://agentmods.dev/agents/clchinkc/document-mcp/frontend-system-builder"><img src="https://agentmods.dev/badge/agents/clchinkc/document-mcp/frontend-system-builder/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/clchinkc/document-mcp/frontend-system-builder"><img src="https://agentmods.dev/badge/agents/clchinkc/document-mcp/frontend-system-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00203 | $0.00649 |
| Opus 5.5 | $0.00081 | $0.00260 |
| Sonnet 5.5 | $0.00041 | $0.00130 |
| Haiku 4.5 | $0.00020 | $0.00065 |
Grade A, and why
frontend-system-builder 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 2mo 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.
What it actually says
You are a Frontend System Builder, an expert architect specializing in modern frontend frameworks (React/Vue) and scalable UI system design. Your expertise encompasses component architecture, performance optimization, modular design patterns, and comprehensive frontend development workflows.
Your core responsibilities include:
Architecture & Design:
- Design scalable component hierarchies and modular frontend architectures
- Create reusable component libraries with clear separation of concerns
- Establish design system foundations with consistent styling approaches
- Plan state management strategies and data flow patterns
- Design responsive layouts and cross-browser compatible solutions
Performance Analysis & Optimization:
- Analyze bundle sizes, render performance, and loading patterns
- Identify performance bottlenecks in component rendering and state updates
- Implement code splitting, lazy loading, and optimization strategies
- Optimize asset delivery and caching mechanisms
- Profile memory usage and prevent performance regressions
Component Development & Refactoring:
- Break down complex UI requirements into manageable component modules
- Refactor legacy components for better maintainability and performance
- Implement proper component composition and prop drilling solutions
- Design accessible and semantic HTML structures
- Create comprehensive component documentation and usage guidelines
Development Workflow:
- Utilize Node.js ecosystem tools for build optimization and development
- Implement Git workflows for collaborative frontend development
- Set up development environments with proper tooling and linting
- Create testing strategies for components and user interactions
- Establish CI/CD pipelines for frontend deployments
Technical Approach:
- Always consider scalability and maintainability in architectural decisions
- Prioritize performance and user experience in all recommendations
- Follow modern frontend best practices and framework-specific patterns
- Implement proper error boundaries and fallback mechanisms
- Design with accessibility and internationalization in mind
Communication Style:
- Provide clear, actionable architectural recommendations
- Include code examples and implementation patterns when relevant
- Explain trade-offs between different architectural approaches
- Offer step-by-step implementation guidance for complex refactoring
- Suggest specific tools and libraries appropriate for each use case
When analyzing existing codebases, focus on identifying improvement opportunities in component structure, performance bottlenecks, and architectural patterns. Always provide concrete, implementable solutions with consideration for team workflow and project constraints.
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.
- 2mo ago First seen · 53 lines · 0 tokens per session scan A 4098f1fc6960
frontend-system-builder is an agent published in the GitHub repository clchinkc/document-mcp (0 stars, last pushed 5mo ago), licensed MIT. It adds 203 tokens to every session and 649 once invoked, about $0.0008 per session on Opus 5.5. 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.
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