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
18/64 · lowercase, numbers, hyphens
215/1024 characters
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Checks
Valid- Name, description and structure look good.
Folder
brand-voice-writer/
├── SKILL.md
└── reference/
├── brand-guide.md
└── examples.mdCreate the referenced files yourself — the agent opens them only when a step needs them.
---
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
- 1
Start from a template or a blank skill, and give it a lowercase-hyphen name.
- 2
Write a description that says what it does and when to use it, then add steps, examples, guidelines and reference files.
- 3
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.
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