skill-builder

skill-builder is a skill for Claude Code from mike-coulbourn/claude-vibes. It costs 51 tokens per session (2,071 once invoked), scanned A, original, MIT.

A guide for creating Skills for Claude Code, which are reusable instruction packages that teach the coding assistant how to handle specific tasks.

In plain words
What is it for?
Use it to plan, structure, name, describe, restrict, and debug personal or project skills, whether they use one file or several files.
Why use it?
It helps you define when a skill should activate and organize its instructions correctly, so the skill is easier to find and works as intended.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: reads .claude/ paths; mentions CLAUDE.md; names the AskUserQuestion tool.

Part of the claude-vibes plugin — 24 skills shipped together

Good fit Use it to plan, structure, name, describe, restrict, and debug personal or project skills, whether they use one file or several files.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mike-coulbourn/claude-vibes/skill-builder
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.

Any agent
npx skills add mike-coulbourn/claude-vibes --skill skill-builder
Clone the repo
git clone --depth 1 https://github.com/mike-coulbourn/claude-vibes

Made for: Claude Code.

Or install claude-vibes, the plugin that ships this one along with the rest of its 24 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 skill-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/mike-coulbourn/claude-vibes/skill-builder/github.svg)](https://agentmods.dev/skills/mike-coulbourn/claude-vibes/skill-builder)
Your own site
<a href="https://agentmods.dev/skills/mike-coulbourn/claude-vibes/skill-builder"><img src="https://agentmods.dev/badge/skills/mike-coulbourn/claude-vibes/skill-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.

agentmods 80×15 button for skill-builder

Your own site · 80×15
<a href="https://agentmods.dev/skills/mike-coulbourn/claude-vibes/skill-builder"><img src="https://agentmods.dev/badge/skills/mike-coulbourn/claude-vibes/skill-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,071 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00051 $0.02071
Opus 5 $0.00026 $0.01035
Sonnet 5 $0.00010 $0.00414
Haiku 4.5 $0.00005 $0.00207

Measured 9d ago against content hash 9131f803363a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

skill-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 9d 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/vibes/skills/skill-builder/SKILL.md · 323 lines

How it starts

The opening of the file, as written. The whole thing — 323 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Builder

Build production-quality Skills for Claude Code with proper structure, discoverable descriptions, and best practices.

Quick Reference

Description Formula: [What it does] + [When to use it] + [Trigger terms users say]

Name Rules: Lowercase letters, numbers, hyphens only; max 64 characters; no spaces

Description Rules: Max 1024 characters; must be specific with trigger terms

The Skill Creation Workflow

Phase 1: Requirements Gathering

Use AskUserQuestion to understand what they need:

  1. What should the Skill do?

    • What capability or expertise should it provide?
    • What tasks should it help with?
  2. When should it activate?

    • What scenarios or contexts?
    • What words/phrases would users say?
    • What file types or operations?
  3. Scope decision

    • Personal Skill (~/.claude/skills/) - just for this user
    • Project Skill (.claude/skills/) - shared with team via git
  4. Structure complexity

    • Single file (simple instructions/examples)
    • Multi-file (scripts, templates, extensive docs)
  5. Tool restrictions

    • Full access (default)
    • Restricted (allowed-tools field for read-only or limited scope)

Phase 2: Description Crafting

The description determines discoverability. Use this proven formula:

[Specific operations] + [When to use] + [Trigger terms]

Example walkthrough:

  • ❌ "Helps with documents" (too vague)
  • ✅ "Extract text and tables from PDF files, fill forms, merge documents. Use when working with PDF files or when user mentions PDFs, forms, or document extraction."

Key elements:

  1. Specific operations: List concrete actions (extract, analyze, generate, validate)
  2. When to use: Scenarios and contexts (when working with X, during Y, for Z tasks)
  3. Trigger terms: Exact words users would say (PDF, forms, commit message, data analysis)

See examples/descriptions.md for more patterns.

Phase 3: Name Validation

Read the full file on GitHub · 323 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 9d ago First seen · 323 lines · 51 tokens per session scan A 9131f803363a

Subscribe to this mod's changes

skill-builder is a skill published in the GitHub repository mike-coulbourn/claude-vibes (39 stars, last pushed 8mo ago), licensed MIT. It adds 51 tokens to every session and 2,071 once invoked, about $0.0003 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.

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