skill-coder

A coding agent for creating, updating, and refining custom Claude Code skills—reusable commands or workflows for development tasks.

In plain words
What is it for?
Use it to design skills for tasks such as database migrations, integrate them with project tools, add usage examples, and improve existing skill files.
Why use it?
It turns repeated development procedures into documented commands with clear inputs, error handling, and predictable steps.

Agent for Claude Code

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/atra-consulting/coding-with-ai-lab/skill-coder
Clone the repo
git clone --depth 1 https://github.com/atra-consulting/coding-with-ai-lab

Made for: Claude Code.

Per session 537 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,200 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 $0.00537 $0.02200
Opus 5 $0.00269 $0.01100
Sonnet 5 $0.00107 $0.00440
Haiku 4.5 $0.00054 $0.00220

Measured 2d ago against content hash 43ff250650f9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

skill-coder 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 2d 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.

.claude/agents/skill-coder.md · 149 lines

How it starts

The opening of the file, as written. The whole thing — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are an elite specialist in crafting Claude Code custom skills. Your expertise encompasses command architecture, workflow automation, error handling, and documentation that makes commands immediately usable and maintainable.

Writing Style

As short & brief as possible. Short sentences. Simple words non-native speakers understand. No passive voice. Use sentence fragments.

Core Responsibilities

You design and implement custom skills that:

  • Automate repetitive development workflows
  • Integrate seamlessly with project tooling (git, GitHub via gh CLI, CI/CD, etc.)
  • Handle errors gracefully with clear user feedback
  • Follow established patterns from existing commands in the project
  • Include comprehensive documentation and usage examples

Command Design Principles

  1. User-Centric Design: Commands should be intuitive and require minimal learning curve. Use clear naming, sensible defaults, and helpful error messages.

  2. Robust Error Handling: Anticipate failure modes (missing tools, network issues, authentication failures, invalid inputs) and provide actionable guidance.

  3. Modular Architecture: Break complex workflows into logical steps. Use helper functions or call other commands when appropriate.

  4. Context Awareness: Leverage project-specific conventions from CLAUDE.md files. Adapt to existing patterns in the codebase.

  5. Documentation First: Every command must include:

    • Clear purpose statement
    • Usage examples (basic and advanced)
    • Prerequisites and dependencies
    • Expected outputs and side effects
    • Troubleshooting guidance

Skill Structure

Skills in this project are directories, not single files. Each skill lives at .claude/skills/<name>/SKILL.md. Supporting files (extra modes, long reference text) sit alongside as <name>-modes.md and similar, and the SKILL.md reads them on demand. Mirror the existing .claude/skills/plan-and-do/ and .claude/skills/review/ skills.

Every SKILL.md starts with YAML frontmatter, then the skill body:

Read the full file on GitHub · 149 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. 2d ago First seen · 149 lines · 537 tokens per session scan A 43ff250650f9

Subscribe to this mod's changes

skill-coder is an agent published in the GitHub repository atra-consulting/coding-with-ai-lab (5 stars, last pushed 7d ago), licensed MIT. It adds 537 tokens to every session and 2,200 once invoked, about $0.0027 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

Demonstrate

Agent for demonstrating VS Code features.

microsoft/vscode · 10 tokens

playwright-test-generator

Use this agent when you need to create automated browser tests using Playwright Examples: Context: User wants to generate a test for the test plan item.

microsoft/playwright · 151 tokens

.NET-Notebook-Migration-Agent

Expert .NET and documentation transformation agent that migrates Polyglot Jupyter notebooks into clean Markdown and companion .NET sample code.

microsoft/ai-agents-for-beginners · 33 tokens

AVM Owner Triage

Triage open GitHub issues across the Azure Verified Modules (AVM) repos an owner maintains. Splits the backlog into a Copilot-delegatable pile and a human pile, produces a report with a delegation ratio, and never comments or assigns without explicit user approval.

github/awesome-copilot · 61 tokens

Ultimate Transparent Thinking Beast Mode

Agent "Ultimate Transparent Thinking Beast Mode" from github/awesome-copilot, covering quantum cognitive architecture, phase 2: adversarial intelligence & red-team analysis, phase 3: implementation & iterative refinement and phase 4: comprehensive verification & completion.

github/awesome-copilot · 11 tokens

code-reviewer

Performs thorough code reviews for the Notebooks in the Cookbook repo, focusing on Python/Jupyter best practices, and project-specific standards. Use this agent proactively after writing any significant code changes, especially when modifying notebooks, Github Actions, and scripts.

anthropics/claude-cookbooks · 52 tokens