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Agent skill

Skill Authoring

by extra-org in extra-org/extra

How to create or restructure a skill so the .ai/skills/ system stays consistent, operational, and trustworthy.

MITAuto-check passedAgent Workflows

Install Skill Authoring

skills CLI
$ npx skills add extra-org/extra --skill skill-authoring -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install extra-org/extra skill-authoring --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/extra-org/extra.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/skill-authoring .claude/skills/skill-authoring && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
skill-authoring
GitHub stars
113
Token cost
~1k tokens
SKILL.md length
437 words
Files
1
Skills in repo
14
Repo updated
First seen
Licence
MIT

At a glance

How to create or restructure a skill so the .ai/skills/ system stays consistent, operational, and trustworthy.

  • Works in 6 steps: Confirm the gap. Ensure no existing… → Copy the template below into… → Fill every section with concrete,… → …
  • Tasks that involve Skill authoring
  • SKILL.md covers Purpose, When to Use This Skill, Files to Read First and Core Principles, plus 5 more sections
  • Calls make

What it does

Skill Authoring is an agent skill from extra-org/extra. How to create or restructure a skill so the .ai/skills/ system stays consistent, operational, and trustworthy. A skill is a short, repeatable playbook — not an essay.

Its SKILL.md is about 1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Agent Workflows, covering Skill authoring. The repository describes itself as: Turn your product into an AI-powered assistant. The licence is MIT.

When your agent uses it

  • Tasks that involve Skill authoring

Example prompts

  • “/skill-authoring”

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

  1. Confirm the gap. Ensure no existing skill already covers the area; prefer
  2. Copy the template below into .ai/skills/.md.
  3. Fill every section with concrete, project-specific instructions (mention
  4. Cross-check against AGENTS.md/ADRs for contradictions.
  5. Add it to .ai/README.md index and, if it maps to a task type, to the
  6. Validate formatting with make check (Markdown only → still run it).

What it can do on your machine

Read from SKILL.md and the folder at commit 023b0a0. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • make

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Skill Authoring loads about 1k tokens when it runs. Until then it costs about 46 tokens; SKILL.md has 437 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~46
When it runs · the whole SKILL.md, loaded when a task matches
~1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from extra-org/extra at commit 023b0a0, republished under its MIT licence (© extra-org). 437 words, ~1,047 tokens.

Download SKILL.mdSave it as .claude/skills/skill-authoring/SKILL.md (or your agent's skills folder).
name
skill-authoring
description
How to create or restructure a skill so the .ai/skills/ system stays consistent, operational, and trustworthy. A skill is a short, repeatable playbook — not an essay.
generated
true
source
.ai/skills/skill-authoring.md
<!--
This file is generated by tools/skills.
Do not edit this file directly.
Edit .ai/skills/skill-authoring.md and run `make generate-ai`.
-->

Skill: Skill Authoring

Purpose

Define how to create new skill files so the .ai/skills/ system stays consistent, operational, and trustworthy. A skill is a short, repeatable playbook — not an essay.

When to Use This Skill

  • Creating a new skill file in .ai/skills/.
  • Substantially restructuring an existing skill.
  • Reviewing a proposed skill for quality and consistency.

Files to Read First

  • AGENTS.md (skills system + architecture rules a skill must not contradict).
  • .ai/README.md (the index a new skill must be added to).
  • An existing high-quality skill as a model (e.g. .ai/skills/code-review.md).
  • Any docs//ADR the new skill will reference.

Core Principles

  • Operational, not academic. A skill tells an agent what to do, step by step. No long prose.
  • Task-oriented and repeatable. Focus on behavior an agent will repeat.
  • Consistent structure. Every skill uses the standard section set (below).
  • Must include when to use it, files to read first, rules, process, checklist, and common mistakes.
  • Never contradicts AGENTS.md, the docs, or ADRs. If it would, you need an ADR/doc change first, not a skill that diverges.
  • References, not duplicates. Link to the authoritative doc/ADR rather than copying its content (which will drift). This is also why skills live only in .ai/ — never copy them into tool-specific folders.
  • Short enough to be used. If it's too long to read before a task, trim it.
  • Includes validation commands (e.g. make check).
Show full SKILL.md (213 more words)Show less

Process

  1. Confirm the gap. Ensure no existing skill already covers the area; prefer improving one over adding a near-duplicate.
  2. Copy the template below into .ai/skills/<name>.md.
  3. Fill every section with concrete, project-specific instructions (mention real layers, files, and commands — not generic advice).
  4. Cross-check against AGENTS.md/ADRs for contradictions.
  5. Add it to .ai/README.md index and, if it maps to a task type, to the AGENTS.md skills mapping.
  6. Validate formatting with make check (Markdown only → still run it).

Template for a new skill file

markdown
---
name: <skill-name>
description: <one-sentence summary of when and why to use this skill>
---

# Skill: <Skill Name>

## Purpose
<one short paragraph: what this skill is for>

## When to Use This Skill
- <situation 1>
- <situation 2>

## Files to Read First
- <file 1>
- <file 2>

## Core Principles
- <non-negotiable principle 1>
- <non-negotiable principle 2>

## Process
1. <step 1>
2. <step 2>

## Checklist Before Finishing
- [ ] <check 1>
- [ ] `make check` passes.

## Common Mistakes to Avoid
- <mistake 1>

## Expected Final Report
<what the agent should report after applying this skill>

Checklist Before Finishing

  • File named .ai/skills/<name>.md and uses the standard sections.
  • Content is operational, concrete, and project-specific.
  • No contradiction with AGENTS.md, docs, or ADRs.
  • References authoritative docs instead of duplicating them.
  • Includes validation commands.
  • Added to .ai/README.md (and AGENTS.md mapping if applicable).
  • make check passes.

Common Mistakes to Avoid

  • Writing a long essay instead of a playbook.
  • Vague, generic advice that isn't tied to this project.
  • Duplicating doc/ADR content that will drift out of sync.
  • Forgetting to register the skill in the README/mapping.
  • Contradicting an existing rule without first updating the ADR/doc.

Expected Final Report

State: the new skill's name and path; the gap it fills; which docs/ADRs it references; where it was registered (README/AGENTS mapping); and confirmation that it matches the standard structure and contradicts nothing.

© extra-org, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .claude/skills/skill-authoring of extra-org/extra.

Open the folder on GitHubat commit 023b0a0

Compare with similar skills

Skill Authoring next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Skill Authoring compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Skill Authoring this skillextra-org/extra113—~1kAutomated safety check: PassMIT
Skill CreatorAzure/azqr79489 repos~8.2kAutomated safety check: PassApache-2.0
Claude Code Skill Developer Guidediet103/claude-code-infrastructure-showcase10k10 repos~3.5kAutomated safety check: PassMIT
Darwin Skill Optimizeralchaincyf/darwin-skill6.2k1 repos~4.7kAutomated safety check: PassMIT
Claude Code Command Developmentanthropics/claude-plugins-official37k10 repos~4.8kAutomated safety check: PassApache-2.0
Claude Code Plugin Structureanthropics/claude-plugins-official37k10 repos~3.4kAutomated safety check: PassApache-2.0

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Categories

Questions about Skill Authoring

What does Skill Authoring do?

How to create or restructure a skill so the .ai/skills/ system stays consistent, operational, and trustworthy. Skill Authoring is an agent skill from extra-org/extra.ai/skills/ system stays consistent, operational, and trustworthy.

When should I use Skill Authoring?

Skill Authoring fits situations like: tasks that involve Skill authoring.

How do I install Skill Authoring in Claude Code?

Run `npx skills add extra-org/extra --skill skill-authoring -a claude-code`. Or copy the skill folder (.claude/skills/skill-authoring in extra-org/extra) into .claude/skills/skill-authoring in your project. Claude Code loads it when a task matches its description.

How do I install Skill Authoring in Codex?

Run `npx skills add extra-org/extra --skill skill-authoring -a codex`. Or copy the skill folder (.claude/skills/skill-authoring in extra-org/extra) into .agents/skills/skill-authoring in your project. Codex loads it when a task matches its description.

Can I use Skill Authoring in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add extra-org/extra --skill skill-authoring -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/skill-authoring, .gemini/skills/skill-authoring, .github/skills/skill-authoring and .opencode/skills/skill-authoring in your project.

What does Skill Authoring need to run?

Going by SKILL.md and its folder, Skill Authoring needs the command-line tools its instructions call (make).

Does Skill Authoring access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Skill Authoring safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Skill Authoring use?

Skill Authoring is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Skill Authoring use?

About 1k tokens (SKILL.md is roughly 4.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Skill Authoring?

Skills that share tags, products or a category with Skill Authoring: Skill Creator (Azure/azqr, 794 stars), Claude Code Skill Developer Guide (diet103/claude-code-infrastructure-showcase, 10k stars), Darwin Skill Optimizer (alchaincyf/darwin-skill, 6.2k stars) and Claude Code Command Development (anthropics/claude-plugins-official, 37k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Skill Authoring?

extra-org (a GitHub organization) maintains it in extra-org/extra, which has 113 GitHub stars. The repository holds 14 skills in this directory. The repository was last updated on September 7, 2026.

Source: extra-org/extra on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.