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A free guide by Mariah Brunner ↗ INSTAGRAM ↗ TIKTOK

Build Claude Skills
That Actually Work

For regular Claude users. No tech skills needed. Exactly how to build a Skill, what to write and how to make Claude use it automatically every time.

A Skill is a set of instructions you write once and save to Claude. After that, Claude knows your workflow, so you stop copy-pasting the same prompt and re-explaining your preferences in every new chat.

Think of it like training a new hire. Instead of re-explaining the job every day, you hand them an onboarding guide. A Skill is that guide for Claude.

How Skills Work: 3 Layers

A Skill isn’t one big block of text. Claude reads it in layers, which is why a good one runs on its own and a bad one never does. (Anthropic)

01

The name and description

Claude checks this tiny header to decide whether the Skill fits what you’re asking right now. A specific description means it runs on its own. A vague one means it never does.

Example. Name email-rewriter. Description: "Rewrites emails to sound clear, warm and professional. Use when someone asks to improve, fix, rewrite or clean up an email."

02

Your step-by-step instructions

Once the Skill fits, Claude reads the rest of the file. This is your process, with your steps, your rules and what the output should look like. Keep it focused on one job.

03

Reference files (optional)

Extra files in the same folder that Claude opens only when the task needs them, like a brand voice doc, sample emails or a template. Mention them by name in your instructions so Claude knows they’re there.

Build And Upload It
  1. Turn on file creation. Go to Settings, then Capabilities, and turn on Code execution and file creation (called Create and edit files in the newer settings layout). Skills need it. They work on every plan, Free included.
  2. Pick a task you repeat. If you’ve explained it to Claude 5 times, that’s your Skill. Emails in your voice, weekly reports and captions in your tone are great first ones.
  3. Make a folder and a SKILL.md file. Name the folder in lowercase with hyphens, like email-rewriter. Inside it, make a plain text file called SKILL.md. The top holds the name (matching the folder) and a description under 200 characters. Your instructions go below.
  4. Zip the folder and upload it. Go to Customize (Claude is renaming it Plugins, so you may see either), then Skills. Click +, then Create skill, then Upload a skill, and pick your ZIP.
  5. Turn it on and test it. Make sure its switch is on in your Skills list. Open a fresh chat and ask for the task without naming the Skill, like "can you help me rewrite this email?" If Claude uses it on its own, your description works.

Most Common Mistake

Zip the folder, not the SKILL.md file inside it. The folder has to sit at the top level of the ZIP, and its name should match the skill name.

Stuck? Anthropic’s guide to custom skills has the full file format and a testing checklist, and its using skills guide covers the settings.

Steal My Starter Skill

Here’s the email Skill from this guide, ready to upload. Install it as-is to see how a Skill feels, then open the file and swap in your own rules.

↓ Download email-rewriter (.zip)
email-rewriter / SKILL.md
--- name: email-rewriter description: Rewrites emails to sound clear, warm and professional. Use when someone asks to improve, fix, rewrite, shorten or clean up an email or message. --- # Email Rewriter ## Steps 1. Read the whole email before changing anything. Figure out who it's to, what it's asking for and the relationship (boss, client, friend, stranger). 2. Keep the original meaning and every fact, date, name and number. Only change tone, clarity and length. 3. Put the main point or ask in the first two sentences. 4. Use short sentences. Cut filler like "I just wanted to reach out" and "I hope this email finds you well." 5. End with one clear, polite next step (a question, a deadline or a yes/no). 6. Match the formality of the original unless the user asks for a different tone. ## Rules - Never use exclamation marks unless the original had them. - Never add promises, prices or dates that weren't in the original. - If something in the email is unclear or might land badly, flag it in one line under the rewrite. ## Output 1. A subject line (only if the email needs one). 2. The rewritten email, ready to paste. 3. One line on what you changed and why. ## Example Original: "Hi, so sorry to bother you again, I just wanted to circle back and see if you maybe had a chance to look at the proposal I sent last week? No worries if not!" Rewrite: "Hi Sam, following up on the proposal I sent last Tuesday. Could you let me know by Friday if you'd like to move forward, or if you have questions I can answer?" What changed: led with the ask, added a deadline, cut the apologies.
Writing It: 3 Things That Matter

01

Write the description like a trigger

Say what it does and when to use it, with the phrases you’d actually type. Too vague and it never runs.

Before: "Helps with writing and content tasks."

After: "Rewrites emails to sound professional. Use when someone asks to improve, rewrite, fix or clean up an email."

02

Steps, not an essay

Numbered steps telling Claude exactly what to do. Skip the backstory. Long reference material goes in its own file.

03

One great example

Show what a perfect result looks like. Claude learns more from one real example than from five paragraphs of explanation.

Let Claude Write It For You

Don’t want to write it from scratch? Paste this into Claude and it interviews you, writes the SKILL.md and gives you test messages.

Skill Builder Interview
You are helping me turn a task I repeat into a Claude Skill. Interview me first, then write the file. The task I keep explaining to you: [DESCRIBE IT, e.g. "turning my meeting notes into a client recap email"] If you can see past chats where I've done this, use them as examples. Step 1. Ask me up to 5 questions, one at a time, about: - What I give you at the start (files, notes, links) - The exact steps I want you to follow, in order - What the finished output looks like (format, length, tone) - Things I always correct or never want - A real example of a result I loved, if I have one Step 2. Write a complete SKILL.md file: - YAML frontmatter at the top with two fields: name: lowercase words joined by hyphens (e.g. client-recap-email) description: under 200 characters. Say what it does AND when to use it, with the actual phrases I'd type. - Then: numbered steps, a short rules list, the output format and one short example of a perfect result. - Keep it under about 500 words. If there's long reference material (a brand guide, sample library), tell me to put it in a separate file and reference it by name. Step 3. Give me 3 test messages I can type in a fresh chat that should trigger the skill WITHOUT naming it, and 1 message that should NOT trigger it. Don't add steps I didn't ask for. If something is unclear, ask instead of guessing.

Tips That Level You Up

One Skill, one job. Claude can use several Skills together, so small and specific beats big and vague. If it doesn’t run, make the description more specific, then upload again and retest. Start with Anthropic’s built-ins for Excel, Word, PowerPoint and PDF to see how Skills feel. Anthropic also shares its own skill-creator Skill that builds Skills with you.