Skill Development

Skill Development is a skill for Claude Code, Codex from ajsai47/holyclaude. It costs 63 tokens per session (5,019 once invoked), scanned A, a copy of skill-development, MIT.

A guide to creating skills for Claude Code plugins. Skills are packaged instructions, workflows, tools, and reference material that give an agent specialized knowledge.

In plain words
What is it for?
Use it to create or improve plugin skills, personas, workflows, bundled scripts, and reference documentation.
Why use it?
It explains how to organize skill files and supporting resources so they are clear, reusable, and easy for an agent to apply.

Skill for Claude CodeCodex

Part of the holyclaude plugin — 11 skills, 9 commands, 14 agents, 6 hooks, 1 MCP server, 5 plugins shipped together

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 skills/ajsai47/holyclaude/skill-development
Any agent
npx skills add ajsai47/holyclaude --skill skill-development
Clone the repo
git clone --depth 1 https://github.com/ajsai47/holyclaude

Made for: Claude Code, Codex.

Or install holyclaude, the plugin that ships this one along with the rest of its 11 skills, 9 commands, 14 agents, 6 hooks, 1 MCP server, 5 plugins.

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 Development

README.md
[![agentmods](https://agentmods.dev/badge/skills/ajsai47/holyclaude/skill-development.svg)](https://agentmods.dev/skills/ajsai47/holyclaude/skill-development)
Your own site
<a href="https://agentmods.dev/skills/ajsai47/holyclaude/skill-development"><img src="https://agentmods.dev/badge/skills/ajsai47/holyclaude/skill-development.svg" alt="Measured on agentmods" height="20"></a>
Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,019 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 98% 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 $0.00063 $0.05019
Opus 5 $0.00032 $0.02509
Sonnet 5 $0.00013 $0.01004
Haiku 4.5 $0.00006 $0.00502

Measured 5d ago against content hash d40080c45d65, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Skill Development 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 5d 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

98% identical to skill-development — 4 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.

plugins/plugin-dev/skills/skill-development/SKILL.md · 638 lines

How it starts

The opening of the file, as written. The whole thing — 638 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Development for Claude Code Plugins

This skill provides guidance for creating effective skills for Claude Code plugins.

About Skills

Skills are modular, self-contained packages that extend Claude's capabilities by providing specialized knowledge, workflows, and tools. Think of them as "onboarding guides" for specific domains or tasks—they transform Claude from a general-purpose agent into a specialized agent equipped with procedural knowledge that no model can fully possess.

What Skills Provide

  1. Specialized workflows - Multi-step procedures for specific domains
  2. Tool integrations - Instructions for working with specific file formats or APIs
  3. Domain expertise - Company-specific knowledge, schemas, business logic
  4. Bundled resources - Scripts, references, and assets for complex and repetitive tasks

Anatomy of a Skill

Every skill consists of a required SKILL.md file and optional bundled resources:

skill-name/
├── SKILL.md (required)
│   ├── YAML frontmatter metadata (required)
│   │   ├── name: (required)
│   │   └── description: (required)
│   └── Markdown instructions (required)
└── Bundled Resources (optional)
    ├── scripts/          - Executable code (Python/Bash/etc.)
    ├── references/       - Documentation intended to be loaded into context as needed
    └── assets/           - Files used in output (templates, icons, fonts, etc.)
SKILL.md (required)

Metadata Quality: The name and description in YAML frontmatter determine when Claude will use the skill. Be specific about what the skill does and when to use it. Use the third-person (e.g. "This skill should be used when..." instead of "Use this skill when...").

Bundled Resources (optional)
Scripts (scripts/)

Executable code (Python/Bash/etc.) for tasks that require deterministic reliability or are repeatedly rewritten.

  • When to include: When the same code is being rewritten repeatedly or deterministic reliability is needed
  • Example: scripts/rotate_pdf.py for PDF rotation tasks
  • Benefits: Token efficient, deterministic, may be executed without loading into context
  • Note: Scripts may still need to be read by Claude for patching or environment-specific adjustments

Read the full file on GitHub · 638 lines

Files

What ships with it

1 file 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. 5d ago First seen · 638 lines · 63 tokens per session scan A d40080c45d65

Subscribe to this mod's changes

Skill Development is a skill published in the GitHub repository ajsai47/holyclaude (11 stars, last pushed 5mo ago), licensed MIT. It adds 63 tokens to every session and 5,019 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 98% identical to skill-development, differing in 4 lines, and is treated as a copy.

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