Building a Claude Skill is simpler than it looks. With a text file and the right conventions, you can turn Claude into a specialist for the kind of tasks you do every day.

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Prerequisites

  • An environment where Claude can load Skills (Claude Code recommended, or Claude Desktop with Skills enabled).
  • A plain text editor.
  • A specific idea of what your Skill should do.

Step 1: define the Skill's purpose

Before writing code, answer:

  • What problem does this Skill solve?
  • When exactly should it activate?
  • What result should Claude produce when it fires?
  • What should the Skill NOT do?

For this tutorial we'll create copy-reviewer: a Skill that reviews marketing copy and suggests improvements.

Step 2: create folder structure

copy-reviewer/
  SKILL.md
  examples/
    before-after-1.md

Step 3: write the frontmatter

---
name: copy-reviewer
description: Reviews marketing copy (emails, ads, landing pages, product copy) and suggests specific improvements for clarity, impact, and conversion. Activates when the user shares text and asks "review this copy", "improve this email", "give me feedback on this landing" or similar.
---
Key tip

The description is your best friend or worst enemy. Explicitly mention words a real user would use ("review", "improve", "feedback") and the concrete formats it handles ("email", "landing", "ad").

Step 4: write the instructions

# Copy Reviewer

## When to apply
User shares marketing text and asks for feedback,
review, or improvement.

## Review process
Follow these steps IN ORDER:
1. Identify the goal (what action should the reader take)
2. Analyze clarity (in 5 seconds, is it obvious?)
3. Mark concrete problems: CLARITY, JARGON, VAGUE PROMISE, WEAK CTA
4. Rewrite the 3 weakest parts with before/after
5. Final verdict: approved / needs major revision / rewrite

## Rules
- Don't use copywriting jargon unless explaining it
- Don't rewrite everything if only spots have issues
- If the text is already good, say so — don't invent problems

Step 5: add reference examples

Examples are gold. A file like examples/before-after-1.md with a real case gives Claude a template to imitate.

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Step 6: install and test

  • Claude Code: place in ~/.claude/skills/ (personal) or .claude/skills/ in the project.

Restart Claude if needed and test with a request that should activate the Skill.

Common mistakes

  • Too generic description: "Helps with text" fires on any text request.
  • Too-long instructions: 200 lines of rules saturate context. Prioritize clarity and examples.
  • No examples: without expected output, results are inconsistent.
  • Overlap with other Skills: differentiate by clear domains.

Iterating your Skill

Every time you use the Skill and the result isn't ideal, ask: was it a user prompt problem or a Skill problem? If the Skill, edit SKILL.md and add the missing rule or example. In 2-3 iterations you'll have a Skill that works 90% of the time.

Conclusion

Creating a Claude Skill needs clarity of purpose, a good description, and a few well-thought instructions. Not programming, but behavior design. Start small (one Skill for one specific task), test, then expand. In a few hours you'll have a personal library that multiplies your productivity.

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