create-skill

create-skill is a skill for Claude Code, Codex from helderberto/agent-skills. It costs 73 tokens per session (2,657 once invoked), scanned A, original, MIT.

A guide for creating new skills for coding agents. It explains how to define the task, inspect related skills, write the main instruction file, and optionally add reference material or helper scripts.

In plain words
What is it for?
Use it to build a skill for a specific task or domain, decide whether it needs executable helpers, and organize its instructions and supporting files.
Why use it?
It provides a repeatable structure so a new skill is clear, focused, and easier for an agent to use consistently.

Skill for Claude CodeCodex

Part of the hb plugin — 40 skills, 6 agents 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/helderberto/agent-skills/create-skill
Any agent
npx skills add helderberto/agent-skills --skill create-skill
Clone the repo
git clone --depth 1 https://github.com/helderberto/agent-skills

Made for: Claude Code, Codex.

Or install hb, the plugin that ships this one along with the rest of its 40 skills, 6 agents.

Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,657 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 $0.00073 $0.02657
Opus 5 $0.00036 $0.01328
Sonnet 5 $0.00015 $0.00531
Haiku 4.5 $0.00007 $0.00266

Measured 3d ago against content hash 3bd5d7c8a6e6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

create-skill 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 3d 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.

skills/create-skill/SKILL.md · 194 lines

How it starts

The opening of the file, as written. The whole thing — 194 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Creating Skills

Process

  1. Gather requirements — ask the user (use AskUserQuestion when available; otherwise present numbered options):
    • What task or domain does the skill cover?
    • What specific use cases should it handle?
    • Does it need executable scripts, or just instructions?
    • Any reference material to include?
  2. Explore existing skillsls skills/ and read 1–2 neighbors to match conventions.
  3. Draft — create SKILL.md; split deep material into references/ if it exceeds ~150 lines; add scripts/ only for deterministic helpers.
  4. Review with user — present the draft and ask:
    • Does this cover your use cases?
    • Anything missing or unclear?
    • Should any section be more or less detailed?

Skill Structure

skill-name/
├── SKILL.md              # Required. Metadata + instructions.
├── references/           # Optional. Long-form docs the agent reads on demand.
│   └── <topic>.md
├── scripts/              # Optional. Deterministic helpers (.sh, .py) called via Bash.
│   └── helper.sh
└── assets/               # Optional. Files used in output (templates, icons, fonts).
    └── template.md

Keep the entry point in SKILL.md. Link from SKILL.md to references/<topic>.md rather than inlining — preserves progressive disclosure.

Progressive disclosure (three levels)

  1. Metadata (name + description) — always in context (~100 words). Sole signal for triggering.
  2. SKILL.md body — loaded when skill triggers. Keep under ~150 lines; the spec ceiling is ~500.
  3. Bundled resources (references/, scripts/, assets/) — loaded on demand or executed without loading.

SKILL.md Template

---
name: skill-name
description: One sentence what it does. Use when [triggers]. Don't use when [anti-triggers].
---

# Skill Name

[body — steps, reference, or both]

A skill's body is built from two content types that mix freely: steps (ordered actions the agent takes) and reference (definitions, rules, facts consulted on demand). A skill can be all steps, all reference, or both — let the content pick the shape. Don't force Workflow / Rules / Error Handling headings onto a skill that doesn't need them; empty scaffolding sections are no-ops (see Failure Modes).

Read the full file on GitHub · 194 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. 3d ago First seen · 194 lines · 73 tokens per session scan A 3bd5d7c8a6e6

Subscribe to this mod's changes

create-skill is a skill published in the GitHub repository helderberto/agent-skills (13 stars, last pushed 2d ago), licensed MIT. It adds 73 tokens to every session and 2,657 once invoked, about $0.0004 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 2026-08-30.

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