skill-creator

A guide and toolkit for creating new Agent Skills that follow the agentskills.io specification. An Agent Skill is a reusable set of instructions and supporting files for an AI agent.

In plain words
What is it for?
Use it to plan, name, document, and structure a new SKILL.md file and its optional scripts, references, or assets.
Why use it?
It provides a defined structure for packaging a skill instead of starting from an empty folder.

Skill for Claude CodeCodex

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/bug-ops/zeph/skill-creator
Any agent
npx skills add bug-ops/zeph --skill skill-creator
Clone the repo
git clone --depth 1 https://github.com/bug-ops/zeph

Made for: Claude Code, Codex.

Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 911 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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 $0.00075 $0.00911
Opus 5 $0.00037 $0.00456
Sonnet 5 $0.00015 $0.00182
Haiku 4.5 $0.00007 $0.00091

Measured 2d ago against content hash 8724edac67c7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

skill-creator scanned grade B with 1 finding 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.

Strips warnings and disclaimersmediumAnti-refusal

Omitting safety caveats hides risk from the user and is a common jailbreak preamble.

4. **Security first** — never include secrets, credentials, or destructive commands without warnings
.zeph/skills/skill-creator/SKILL.md · 127 lines

How it starts

The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Creator

Create a new skill following the agentskills.io specification (https://agentskills.io/specification).

Step 1: Gather requirements

Ask the user:

  1. What should the skill do?
  2. What tools or commands does it need?
  3. Does it need references, scripts, or assets?

If the user already provided enough context, skip asking and proceed.

Step 2: Choose a name

Rules for the name field:

  • 1-64 characters
  • Lowercase letters, numbers, hyphens only (a-z, 0-9, -)
  • Must NOT start or end with -
  • Must NOT contain consecutive hyphens (--)
  • Must match the parent directory name

Step 3: Write the description

Rules for the description field:

  • 1-1024 characters
  • Must describe WHAT the skill does AND WHEN to use it
  • Include keywords that help semantic matching

Good:

description: Extract text and tables from PDF files, fill PDF forms, and merge multiple PDFs. Use when working with PDF documents or when the user mentions PDFs, forms, or document extraction.

Bad:

description: Helps with PDFs.

Step 4: Create the directory structure

.zeph/skills/<skill-name>/
├── SKILL.md              # Required
├── scripts/              # Optional: executable scripts
├── references/           # Optional: detailed docs loaded on demand
└── assets/               # Optional: templates, schemas, data files

Step 5: Write SKILL.md

Use this template:

---
name: <skill-name>
description: <what it does and when to use it>
compatibility: <only if environment requirements exist>
metadata:
  author: zeph
  version: "1.0"
---
# <Skill Title>

<One-line summary of what this skill does.>

## Step 1: <First action>

<Instructions with code blocks showing exact commands or tool invocations.>

## Step 2: <Next action>

<Continue step-by-step. Keep instructions concrete and unambiguous.>

Optional frontmatter fields

Field When to use
license Skill has specific licensing terms
compatibility Skill requires specific binaries, network, or environment
metadata Extra key-value pairs (author, version, tags)
allowed-tools Pre-approve specific tools (experimental)

Read the full file on GitHub · 127 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 · 127 lines · 75 tokens per session scan B 8724edac67c7

Subscribe to this mod's changes

skill-creator is a skill published in the GitHub repository bug-ops/zeph (57 stars, last pushed 8d ago), licensed MIT. It adds 75 tokens to every session and 911 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it B with 1 finding (strips warnings and disclaimers). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.