What makes a good skill description?

It states what the skill does and when to use it, in the third person — e.g. “Extracts totals from invoice PDFs. Use when the user shares an invoice.” Agents decide whether to load a skill from this line alone.

Where do I put the skill folder?

For Claude Code, in .claude/skills/ inside a project or ~/.claude/skills/ for all projects. In the Claude apps you can upload the folder as a .zip from the skills section of settings.

How long should SKILL.md be?

Keep it focused — under about 500 lines. Move long reference material, schemas and examples into separate files that the instructions link to.

Can a skill include scripts?

Yes. A skill folder can contain scripts, templates and data files alongside SKILL.md; the instructions tell the agent when to use them.

SkillT3 · AI builders

Agent Skill Builder — Create a SKILL.md

Turn your team's know-how into an Agent Skill that Claude and other agents load on demand.

100% free
No sign-up
Runs in your browser

What is an Agent Skill?

A skill is a folder with a SKILL.md file: a short YAML header (name + description) and plain Markdown instructions, plus any reference files it needs. Agents like Claude read only the header up front and load the rest on demand — when a task matches the description.

For business owners

Write down how your team does a job once — your brand voice, your invoice process — and the AI follows it every time, without you pasting the same instructions into every chat.

For developers

Put the folder in .claude/skills/ (project) or ~/.claude/skills/ for Claude Code, or zip it and upload it in the Claude app's skill settings. Keep SKILL.md lean; move detail into referenced files.

Build your skill

Start from a template

Skill name

18/64 · lowercase, numbers, hyphens

Title (heading)

Description — what it does + when to use it

215/1024 characters

Overview (optional)

Instructions (in order)

1.Read reference/brand-guide.md for tone, vocabulary and banned words before writing.
2.Identify the channel (website, email, social, ad) and apply its length limits from the guide.
3.Draft the copy, leading with the customer benefit in the first sentence.
4.Check the draft against the banned-words list and the do/don't examples; fix any issues.
5.Return the final copy, then a one-line note on the tone choices you made.

Examples (optional)

Guidelines (one per line)

Referenced files (loaded only when needed)

Limit which tools the skill may use (allowed-tools)

Checks

Valid

Name, description and structure look good.

Folder

brand-voice-writer/
├── SKILL.md
└── reference/
    ├── brand-guide.md
    └── examples.md

Create the referenced files yourself — the agent opens them only when a step needs them.

SKILL.md

---
name: brand-voice-writer
description: Rewrites or drafts marketing copy in the company's brand voice using the tone rules and word lists in the brand guide. Use when the user asks for website copy, social posts, emails or ads that should sound on-brand.
---

# Brand Voice Writer

Turns rough notes or existing copy into on-brand text that follows our voice, vocabulary and formatting rules.

## Instructions

1. Read reference/brand-guide.md for tone, vocabulary and banned words before writing.
2. Identify the channel (website, email, social, ad) and apply its length limits from the guide.
3. Draft the copy, leading with the customer benefit in the first sentence.
4. Check the draft against the banned-words list and the do/don't examples; fix any issues.
5. Return the final copy, then a one-line note on the tone choices you made.

## Examples

### Example 1

**Input:**

Write a LinkedIn post announcing our new same-day delivery in Pune.

**Output:**

Same-day delivery is now live in Pune. Order before 2 pm and it's at your door by evening — no extra charge for orders over ₹999. …

## Guidelines

- British spelling (colour, optimise).
- Short sentences; active voice; no jargon unless the audience uses it.
- Never invent statistics, prices or customer quotes.

## Reference files

Read these only when the task needs them:

- [reference/brand-guide.md](reference/brand-guide.md) — Tone, vocabulary, banned words and channel limits.
- [reference/examples.md](reference/examples.md) — Approved before/after copy samples.

How it works

How to use SkillT3

Start from a template or a blank skill, and give it a lowercase-hyphen name.

Write a description that says what it does and when to use it, then add steps, examples, guidelines and reference files.

Fix any flagged checks, download SKILL.md and place the folder where your agent looks for skills.

About

About this tool

Agent Skills are folders of instructions that AI agents such as Claude can load when a task needs them. Each skill has a SKILL.md file: a short YAML header with a name (lowercase letters, numbers and hyphens, up to 64 characters) and a description of what it does and when to use it (up to 1,024 characters), followed by Markdown instructions and links to any reference files.

Because the agent reads only the name and description until a task matches, you can give it many skills without cluttering every conversation. That makes skills ideal for repeatable work: writing in your brand voice, producing SEO briefs, extracting invoice data, reviewing code or replying to customers.

SkillT3 guides you through each part, validates the name and description as you type, shows the folder structure, and gives you a SKILL.md to download. Start from one of five templates, then replace the examples and rules with your own.

Frequently asked questions

Free proposal

Want AI working inside your business? We set up assistants, automations and MCP connectors.

No obligation. A real strategist replies within 24 hours.

Keep going

More free tools

All free tools

MCP BuilderT3NewConnect AI assistants to your tools: pick MCP servers and get the exact config file.PromptT3PopularWrite clear, structured prompts for ChatGPT, Claude and Gemini — with a quality score.T3 AssistantNewAsk one marketing question at a time and get a clear, practical answer.LLMsT3NewTurn your sitemap into an llms.txt file that guides AI tools to your best pages.

Done-for-you

Let's put AI to work in your business

Free tools show you the problem. The T3 team fixes it, with a clear plan and pricing up front.

Talk to us Run a free website audit