What a skill is and when to make one

A skill is a packaged way of working that Claude can pick up whenever it is relevant. Think of it as a short training manual you write once, after which Claude follows it in any chat that needs it. This article explains what a skill is made of, how it differs from Projects and prompts, and when it is worth making one.

What a skill is

A skill is a folder with at least one file, SKILL.md. That file has two parts:

1. A short header with a name and a description. The description tells Claude what the skill does and when to use it.
2. The instructions: plain text Claude follows when the skill is active, such as steps, rules, examples and checklists.

The folder can also hold extra files: templates, reference documents, examples or small scripts.

house-style/
├── SKILL.md            (required: name, description, instructions)
├── tone-of-voice.md    (optional reference)
├── examples.md         (optional good and bad examples)
└── scripts/
    └── check_length.py (optional helper script)

How Claude uses a skill

Claude does not read every skill in full all the time. At the start it only sees each skill’s name and description. When your request matches a description, Claude opens that skill and follows the instructions, and only reads the extra files when it needs them.

That has two practical effects:

• You can install many skills without cluttering every chat.
• The description decides everything. If it is vague, Claude will not know when to use the skill.

Note: Anthropic ships some skills already, for example the ones that let Claude create Word, Excel, PowerPoint and PDF files. Skills need code execution and file creation to be switched on in your Claude settings.

Skills, Projects and prompts compared

Tool	Best for	Scope
Prompt	A one-off task	One message or chat
Project	Background about one subject: a client, product or topic	Chats inside that Project
Skill	A repeatable way of working: a process, format or standard	Any chat where it is relevant
CLAUDE.md	Rules for one code or website folder in Claude Code	One project folder

A simple rule: Projects hold knowledge about a thing, skills hold know-how about a task. A client’s price list belongs in a Project. “How we write a proposal” belongs in a skill, because it applies to every client.

Where skills work

The same skill format works across Claude:

• In the Claude apps (web and desktop), where you upload a skill in your settings.
• In Claude Code, where skills are folders on your computer or in a project.
• Through the Claude API, for developers.

Skills are available on every plan, including Free. On Team and Enterprise plans, an admin can also share skills with the whole organisation.

When to make a skill

Make a skill when you notice one of these:

• You paste the same instructions into chats again and again.
• A task has fixed steps and people keep forgetting one.
• Output must follow a standard: house style, report layout, naming rules, legal wording.
• You want colleagues to get the same quality as your best person on the job.
• The work needs a template or a small script every time.

When not to

• One-off tasks. Just write a good prompt.
• Background on one client. Use a Project.
• Information that changes daily, such as stock levels or calendars. Use a connector so Claude reads the live source.

Real-world examples

• Agency house style. How the agency writes: tone, banned words, spelling choices, heading rules, and before-and-after examples. Every writer and every chat gets the same voice.
• Astro site architecture. For teams that build websites with Astro: the folder structure, how pages and content collections are set up, naming conventions and a checklist for new sections. Claude Code uses it whenever someone adds a page or component.
• Proposal writer. The sections a proposal must have, how to estimate, which disclaimers to include, and a template file.
• Monthly report. Which numbers to pull, how to compare months and the fixed layout the client expects.

Next steps

• Create a skill
• Install and share skills
• Give Claude lasting context with Projects