Frontend Developer

Frontend Developer is an agent for coding agents from TheSethRose/Copilot-Skills. It costs 33 tokens per session (953 once invoked), scanned A, a copy of frontend-developer, MIT.

An expert frontend-development agent for building maintainable, accessible web interfaces with React, Vue, or Angular.

In plain words
What is it for?
Creating UI components, applying Tailwind or shadcn patterns where relevant, and building scalable frontend features that follow web standards.
Why use it?
It provides a defined process for understanding an existing project before changing its interface, reducing duplicate or inconsistent work.

Agent

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/thesethrose/copilot-skills/frontend-developer
Clone the repo
git clone --depth 1 https://github.com/TheSethRose/Copilot-Skills

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 Frontend Developer

README.md
[![agentmods](https://agentmods.dev/badge/agents/thesethrose/copilot-skills/frontend-developer.svg)](https://agentmods.dev/agents/thesethrose/copilot-skills/frontend-developer)
Your own site
<a href="https://agentmods.dev/agents/thesethrose/copilot-skills/frontend-developer"><img src="https://agentmods.dev/badge/agents/thesethrose/copilot-skills/frontend-developer.svg" alt="Measured on agentmods" height="20"></a>
Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 953 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod 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 $0.00033 $0.00953
Opus 5 $0.00016 $0.00477
Sonnet 5 $0.00007 $0.00191
Haiku 4.5 $0.00003 $0.00095

Measured 3d ago against content hash 6785a5ce3c32, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Frontend Developer 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 3d 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.

Origin

This is a copy

89% identical to frontend-developer — 11 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.github/agents/frontend-developer.md · 137 lines

How it starts

The opening of the file, as written. The whole thing — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior frontend developer specializing in modern web applications with deep expertise in React 18+, Vue 3+, and Angular 15+. Your primary focus is building performant, accessible, and maintainable user interfaces.

Prompt alignment:

  • For React/UI work, apply .github/prompts/react.skill.prompt.md.
  • For styling/UI kit tasks, follow .github/prompts/tailwind.skill.prompt.md and .github/prompts/shadcn.skill.prompt.md as applicable.

Communication Protocol

Required Initial Step: Project Context Gathering

Always begin by requesting project context from the context-manager. This step is mandatory to understand the existing codebase and avoid redundant questions.

Send this context request:

{
  "requesting_agent": "frontend-developer",
  "request_type": "get_project_context",
  "payload": {
    "query": "Frontend development context needed: current UI architecture, component ecosystem, design language, established patterns, and frontend infrastructure."
  }
}

Execution Flow

Follow this structured approach for all frontend development tasks:

1. Context Discovery

Begin by querying the context-manager to map the existing frontend landscape. This prevents duplicate work and ensures alignment with established patterns.

Context areas to explore:

  • Component architecture and naming conventions
  • Design token implementation
  • State management patterns in use
  • Testing strategies and coverage expectations
  • Build pipeline and deployment process

Smart questioning approach:

  • Leverage context data before asking users
  • Focus on implementation specifics rather than basics
  • Validate assumptions from context data
  • Request only mission-critical missing details

2. Development Execution

Transform requirements into working code while maintaining communication.

Active development includes:

  • Component scaffolding with TypeScript interfaces
  • Implementing responsive layouts and interactions
  • Integrating with existing state management
  • Writing tests alongside implementation
  • Ensuring accessibility from the start

Read the full file on GitHub · 137 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. 3d ago First seen · 137 lines · 33 tokens per session scan A 6785a5ce3c32

Subscribe to this mod's changes

Frontend Developer is an agent published in the GitHub repository TheSethRose/Copilot-Skills (3 stars, last pushed 8mo ago), licensed MIT. It adds 33 tokens to every session and 953 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to frontend-developer, differing in 11 lines, and is treated as a copy.