What is creating-agent-skills?

A guide for creating Claude Code Skills, which are instruction files that teach an agent how to handle particular tasks.

Use it to create, improve, or understand SKILL.md files and the design of Claude Code Skills.

It helps ensure skills are written clearly and follow the expected file structure and practices.

creating-agent-skills — Skill for Claude Code by davekilleen/Dex

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 davekilleen/Dex --skill create-agent-skills

Clone the repo

git clone --depth 1 https://github.com/davekilleen/Dex

Made for: Claude Code.

Or install compound-engineering, the plugin that ships this one along with the rest of its 17 skills, 19 commands.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/davekilleen/dex/create-agent-skills/github.svg)](https://agentmods.dev/skills/davekilleen/dex/create-agent-skills)

Your own site

<a href="https://agentmods.dev/skills/davekilleen/dex/create-agent-skills"><img src="https://agentmods.dev/badge/skills/davekilleen/dex/create-agent-skills/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/davekilleen/dex/create-agent-skills"><img src="https://agentmods.dev/badge/skills/davekilleen/dex/create-agent-skills.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,591 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.

Model	Per session	Once invoked
Fable 5.1	$0.00044	$0.01591
Opus 5.5	$0.00018	$0.00636
Sonnet 5.5	$0.00009	$0.00318
Haiku 4.5	$0.00004	$0.00159

Measured 2mo ago against content hash f39947f8a5c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

creating-agent-skills 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.

Origin

Copies of this mod

3 near-identical copies found in the catalogue:

create-agent-skills — 95% identical, 25 lines differ
creating-agent-skills — 91% identical, 55 lines differ
creating-agent-skills — 84% identical, 11 lines differ

.claude/plugins/compound-engineering/skills/create-agent-skills/SKILL.md · 300 lines

How it starts

The opening of the file, as written. The whole thing — 300 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Creating Agent Skills

This skill teaches how to create effective Claude Code Skills following Anthropic's official specification.

Core Principles

1. Skills Are Prompts

All prompting best practices apply. Be clear, be direct. Assume Claude is smart - only add context Claude doesn't have.

2. Standard Markdown Format

Use YAML frontmatter + markdown body. No XML tags - use standard markdown headings.

---
name: my-skill-name
description: What it does and when to use it
---

# My Skill Name

## Quick Start
Immediate actionable guidance...

## Instructions
Step-by-step procedures...

## Examples
Concrete usage examples...

3. Progressive Disclosure

Keep SKILL.md under 500 lines. Split detailed content into reference files. Load only what's needed.

my-skill/
├── SKILL.md              # Entry point (required)
├── reference.md          # Detailed docs (loaded when needed)
├── examples.md           # Usage examples
└── scripts/              # Utility scripts (executed, not loaded)

4. Effective Descriptions

The description field enables skill discovery. Include both what the skill does AND when to use it. Write in third person.

Good:

description: Extracts text and tables from PDF files, fills forms, merges documents. Use when working with PDF files or when the user mentions PDFs, forms, or document extraction.

Bad:

description: Helps with documents

Skill Structure

Required Frontmatter

Field	Required	Max Length	Description
`name`	Yes	64 chars	Lowercase letters, numbers, hyphens only
`description`	Yes	1024 chars	What it does AND when to use it
`allowed-tools`	No	-	Tools Claude can use without asking
`model`	No	-	Specific model to use

Naming Conventions

Use gerund form (verb + -ing) for skill names:

processing-pdfs
analyzing-spreadsheets
generating-commit-messages
reviewing-code

Read the full file on GitHub · 300 lines

Files

What ships with it

25 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.

2mo ago First seen · 300 lines · 44 tokens per session scan A f39947f8a5c9

Subscribe to this mod's changes

creating-agent-skills is a skill published in the GitHub repository davekilleen/Dex (515 stars, last pushed 14d ago), licensed MIT. It adds 44 tokens to every session and 1,591 once invoked, about $0.0002 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 2026-08-30.

Building agents Claude Code ai-assistant anthropic cursor mcp personal-knowledge-management

creating-agent-skills next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
creating-agent-skillsdavekilleen/Dex	Skill	515	14d ago	MIT	A	44	Claude Code
nft-standardswshobson/agents	Skill	42k	4d ago	MIT	A	48	Claude Code
istio-traffic-managementwshobson/agents	Skill	42k	4d ago	MIT	A	40	Claude Code
projection-patternswshobson/agents	Skill	42k	4d ago	MIT	A	36	Claude Code
9router-web-searchdecolua/9router	Skill	32k	yesterday	MIT	A	74	Claude Code, Codex
microservices-patternswshobson/agents	Skill	42k	4d ago	MIT	A	38	Claude Code
track-managementwshobson/agents	Skill	42k	4d ago	MIT	A	44	Claude Code