How to Create Your Own Skills for Claude Code — Complete Tutorial

Skills are Claude Code's most powerful feature -- and also the least explored. While most users stick to individual prompts, those who master skills transform Claude Code into a personalized assistant that knows your patterns, follows your rules and delivers consistent results.

In this tutorial, you will learn how to create a skill from scratch. You don't need to know how to program. Skills are written in Markdown, with instructions in natural language. If you know how to explain a task in writing, you know how to create a skill.

In the end, you will have a functional skill installed and ready to use. Let's build a skill togetherautomated code reviewas a practical example.

1. What are skills in Claude Code

A skill is a set of persistent instructions that Claude Code follows when you invoke it. Unlike a prompt that you type and discard, a skill is saved in your project and can be reused infinite times.

In practice, it works like this:

1. You create a Markdown file with detailed instructions
2. Save in the correct directory (.claude/commands/)
3. Summons with/nome-da-skillat Claude Code
4. Claude follows the skill instructions precisely

Skills solve three fundamental problems with setote prompts:

• Inconsistency:prompts generate different outputs each execution. Skills standardize format and quality
• Forgetfulness:you don't need to remember all the details of the prompt every time. Everything is documented in the skill
• Reusability:write once, use forever. Share with your team or across projects

2. Folder and file structure

The structure of a skill in Claude Code is simple:

Each file.mdinside.claude/commands/automatically becomes a slash command available in Claude Code. The file name (without the extension) is the command name.

File	Command
code-review.md	/code-review
deploy-checklist.md	/deploy-checklist
seo-audit.md	/seo-audit

For more complex skills with evals and references, the structure can be expanded:

3. Anatomy of a skill: the .md file

A skill's Markdown file has a simple but powerful structure. Let's dissect each part:

Key elements of a good skill

• Context:defines the "role" that Claude should assume. This drastically influences the quality of the output
• Instructions:step by step of what to do. The more specific, the better
• Output format:defines exactly how the result should be presented. Ensures consistency between runs
• Restrictions:negative limits and rules (what NOT to do). Prevents Claude from rambling or generating noise

4. Step-by-step example: creating a code review skill

Let's create the complete skin, from scratch until the first run.

Step 1: Create the folder structure

Step 2: Create the skill file

Step 3: Write the instructions

Open the file.claude/commands/review.mdand write:

Step 4: Test the skill

Ready. Your skill is working. Every time you type/review, Claude Code will follow these instructions exactly.

5. Evals folder: testing your skill

The folderevals/allows you to test your skill systematically. Each eval is a test scenario that verifies whether the skill produces the expected result.

eval example

Evals do two things: validate that the skill works as expected and document the desired behavior for when you need to update the instructions.

6. References folder: additional context

The folderreferences/stores documents that the skill can consult during execution. This allows skills to access specialized context without cluttering the main file.

In the skill, you reference these files:

Claude Code reads the referenced files and uses them as additional context. This is especially useful for rules specific to your company or project that do not fit in the skill file.

7. Where to save: project vs global

There are two places to save skills:

Location	Path	Scope	When to use
Project	.claude/commands/	Only available in this project	Project-specific skills (review, deployment, etc.)
Global	~/.claude/commands/	Available in all projects	Generic skills that you use in any project

Recommendation

• Project skills:code review (each project has different standards), deploy checklist, specific tests
• Global Skills:README generator, .gitignore creation, dependency analysis, commit message formatting

If a project skill works so well that you want to use it in everything, copy it to the global directory. Simple.

8. Good practices for professional skills

After creating dozens of skills, these are the patterns that differentiate amateur skills from professional ones:

1. Be specific in context

Bad: "You are a developer." Good: "You are a senior Node.js developer with experience in REST APIs, familiar with Express, Prisma, and PostgreSQL. You prioritize security over convenience."

2. Set the output format explicitly

Don't let Claude decide how to format. If you want a table, specify the columns. If you want bullets, specify the pattern. Format consistency is essential for skills you will use repeatedly.

3. Include restrictions (what NOT to do)

Unconstrained skills tend to produce verbose and noisy output. Add negative rules: "Do not explain basic concepts", "Do not suggest cosmetic changes", "Limit to 10 items in the output".

4. Use input/output examples

If possible, include an example of what the output should look like in the skill. This reduces ambiguity drastically:

5. Iterate and refine

Your first version will not be perfect. Use the skill 5-10 times, observe where the output differs from what was expected and adjust the instructions. The best skills go through several iterations.

6. Document optional tometers

Skills can accept arguments. Document this at the beginning of the file: