1You repeat the same instructions every time

In a new conversation, Claude doesn’t remember how you work. So you paste everything in again: the tone, the length, the prices. When the list is long, something always gets left out.

A skill solves this. You write the instructions once. Claude starts following them whenever you make that kind of request.

Débora responds to about fifteen bath and grooming price requests a day. Before, she pasted eight lines with the price list and the shop’s tone into Claude. With the skill, she only pastes the customer’s message.

2The skill opens on its own when the request matches

You don’t need to call the skill by name. Claude looks at the list of your skills and reads a short sentence for each one: its description. If the request matches, Claude opens that skill and follows what’s written.

The others stay closed and don’t get in the way. That’s why you can have several skills, one for each task.

Raul has two skills: one for employment law opinions and another for client update emails. When he asks, "summarize today’s hearing for the client," Claude opens only the email skill.

3It works for things that repeat the same way

Writing a skill takes about twenty minutes. It’s worth it when a task comes up every week and you want the same result every time.

Three cases don’t call for a skill. A one-time task can be handled in the conversation. Information that changes every day, like today’s schedule, doesn’t fit a fixed recipe. And a rule that applies to every conversation belongs in personal preferences, which are in the app’s Settings.

Débora sorted her tasks into two cards before creating her first skill.

1Claude chooses by the label

A skill has two parts that matter here: its name and its description. When you make a request, Claude hasn’t read any skill in full yet. It only has these two lines for each one.

The name is lowercase, with a hyphen in place of a space. Don’t worry about that: in lesson 5, Claude will write the name for you.

That’s why the description is the most important part. Great instructions are no use if the skill is never opened.

Raul’s first skill had the description "Helps with legal documents." He requested an employment law opinion, and Claude didn’t open the skill: the sentence didn’t mention employment law opinions.

2Say what it does and when to use it

A good description has two parts. The first says what the skill does, starting with a verb: "Builds," "Answers," "Writes." The second says when to use it, with the situations where it should be used.

Write as if you’re introducing the skill to someone else. Avoid "I am" or "you should": the description talks about the skill, not to Claude.

Raul rewrote the vague sentence. Take a look at both cards.

3Use the words you use when you make a request

Claude compares your request with the description. If you write “notice that a pet is ready” and the description says “notification of service completion,” the connection is weak. Put the words you actually say in the description.

Débora tested two descriptions for the same skill. She made the same request both times.

1First, turn on file creation

A skill only works if Claude can open and create files in the conversation. This permission has a long name: Code execution and file creation. It only lets Claude create files inside the conversation: nothing leaves your computer.

On individual plans, including the free plan, you turn it on yourself. In a company account, the account manager enables it for everyone.

Débora opened Claude on the store computer and found the switch turned off. It took just one click.

2The list is under Customize › Skills

With the switch on, the app shows the list of skills. There you'll see Anthropic's ready-made skills—the company that makes Claude—followed by your own. Each one has its own on/off switch. Note: these are two different places. The general switch is under Settings; the list is under Customize.

The ready-made skills handle office files: Word, Excel, PowerPoint, and PDF. You don't need to call any of them by name.

Raul checked the list before creating anything. All four were on, and he saw where his skill would appear.

3Make a request and watch the skill work

Now make a request that calls for a file. Claude sees that the task fits the Word skill, reads its instructions, and creates the document.

To be sure, open Claude's reasoning. It's just above the answer, collapsed into a line. Tap it and look for the skill's name. The ready-made skills appear under the file type name in English: the Word one is "docx".

Raul asked for a list of documents the client brings to the first consultation. He received a Word file ready to print.

1A folder with a text file

Every skill is a folder. Inside it is a plain text file called SKILL.md. The ".md" at the end is just the file type, like Word’s ".docx". Only this file is required.

The folder name is the skill name, in lowercase, with a hyphen in place of each space. If the task needs a model or a large table, those files go in the same folder.

Raul’s employment law opinion skill is a folder with two files: SKILL.md and the opinion template the office has used for years.

2Header on top, instructions below

SKILL.md starts with a header, between two lines of three dashes. It contains the name and description you practiced in lesson 2. Didn’t take lesson 2? The description is the sentence that says what the skill does and when to use it.

Below the header are the instructions, written for someone new to the team. At the end, there’s an example of a good response.

This is Débora’s bath and grooming estimate skill, in full. Read from top to bottom.

---
name: orcamento-banho-tosa
description: Responds to bath and grooming estimate requests using the store’s table and tone. Use when a customer asks the price of a bath, grooming, or a package.
---

# Bath and grooming estimate

## How to respond
1. Greet the customer by name if their message includes it.
2. Give the price from the table. If you don’t know the dog’s size, ask first: the price depends on size.
3. Offer to schedule an appointment and end with a question.
4. Keep it short: the customer reads on a phone.

## Table
Small: bath R$ 60, bath and grooming R$ 80
Medium: bath R$ 70, bath and grooming R$ 95
Large: bath R$ 90, bath and grooming R$ 130

## Example
Customer: "How much is grooming for my shih tzu?"
Response: "Hi! A shih tzu is small: bath and grooming is R$ 80. Would you like to schedule an appointment? Tell me which day works best."

3Explain why instead of shouting orders

Claude takes what’s written in the skill literally. All-caps orders with “never” and “always” make it overdo the rule. A sentence explaining why works better: it understands when the rule applies.

Raul had written the rule about legal summaries the old way. See what changed when he explained why.

1Start with the right request

Anthropic provides a ready-made skill that teaches Claude to create skills: skill-creator. Ask Claude to use it, describe the task, and share what you already have.

Before writing, it asks questions. It’s a short interview about how you do the task.

Raul opened a new conversation and pasted the request below. He got three questions before Claude wrote anything.

2Answer with real examples

The quality of the skill depends on your answers. “The usual” becomes a vague instruction, and Claude fills in the rest with the most common approach. A real example gives it a rule it can follow.

Débora created the budgeting skill. Claude asked, “What if the client doesn’t say how big the pet is?” See the two possible answers.

3Review the text and ask for the ZIP

When it’s done, Claude shows the skill files next to the conversation. Read SKILL.md and check three things. The name at the top matches the folder name. Your description is in the header. And there’s an example at the end.

Want to change a section? Ask in the conversation, the way you would ask a person. Then ask for the whole folder as a ZIP file.

Raul asked to change a word and then prepare the file to download.

1Four steps to the list

Your skill is added from the same place where you saw the ready-made ones in lesson 3. Haven’t taken lesson 3? First, click your name at the bottom of the sidebar menu, go to Settings › Capabilities, and turn on the “Code execution and file creation” toggle.

Have the ZIP file from lesson 5 ready. If it’s still in the Downloads folder, move it to Documents. Skipped lesson 5? Use Débora’s example ZIP to practice uploading.

Débora uploaded it on the shop computer, between one bath and grooming appointment and the next. It took less than two minutes.

2Check that it was added

It worked if the skill appears in the list with its name and description, and its toggle is on. Only you can see it. In a company account, other people get it only if you share it.

The most common upload mistake is choosing the wrong file: a ZIP without SKILL.md inside, or the SKILL.md file by itself.

Raul made a mistake the first time. Look at the two cards.

3Make a regular request and check

Now don’t call the skill by name. Make the request as you would on a workday. If the description is good, Claude recognizes the task and opens the skill on its own.

Then open the reasoning: it’s collapsed into a line just above the answer. Tap it and look for the skill’s name.

There’s a second way to check, without opening anything: the answer uses something only the skill has, such as the price from its table. If the block doesn’t appear, ask in the conversation: "Did you use any skills in this answer? Which one?"

Débora pasted a new client’s message without saying anything else.

1Ask the way you really would

When you’re in a hurry, no one writes a request the same way twice. Your skill needs to open both ways. Try a full sentence and a shortened version, like you’d type on your phone.

How can you tell if it opened? Tap reasoning, just above the answer, and look for the skill’s name. Or check whether the answer uses something only the skill has, such as a price from the price list. If the block doesn’t appear, ask: "Did you use any skills in this answer? Which one?"

If one version fails, the problem is almost always in the description: it’s missing the words you used in that version of the request.

Débora tested two real messages from customers. The second was written the way many people write on WhatsApp.

2A similar request that isn't hers

The reverse test matters too. Make a request from the same area, but for a different task. The skill should stay closed.

If it opens when it shouldn't, the description is too broad and will get in the way of requests that aren't meant for it.

Raul asked for a short email to the client. The employment law opinion skill shouldn't have come in. See what happened, and how it looked after the fix taught in lesson 8.

3Compare with the skill turned off

You still need to know whether the skill improves the result. Turn off its switch in Customize › Skills, open a new conversation, and repeat one of the requests. Then turn it back on.

Débora repeated the request about the medium poodle with the skill turned off.

1Every failure has its place for a fix

The notes from lesson 7 show you where to make changes. If the skill didn't open, or opened when it shouldn't have, the problem is in the description. If it opened and the answer was wrong, the problem is in the instructions or the example.

Change one thing at a time and test again. That way, you know what fixed it.

In lesson 7, the request "how much to give my little pet a trim?" didn't open Débora's skill. She changed only the description.

2Request the correction and replace the version

You don’t need to rewrite the skill. Go back to the conversation where it was created, in lesson 5: it’s in the recent conversations list in the side menu. Can’t find it? Open a new conversation and attach the skill ZIP from Documents using the paperclip button. Describe the problem and ask for only the necessary change, with the new ZIP at the end.

To replace the version, first save the new ZIP in Documents; the old one will still be there. Then open the skill in Settings › Skills, click the three dots (…), choose Delete, and upload the new ZIP using the steps from lesson 6.

Raul’s test showed that the employment law opinion skill opened for a simple email. He went back to the conversation from lesson 5.

3What shouldn’t become a skill

After making your first one, you may want to turn everything into a skill. Three things fit better elsewhere in the app. A rule for every conversation belongs in personal preferences. A client’s matter, with documents and history, belongs in a project. Information that changes all the time comes through a connector.

And use one skill per task. Several small ones work better than one huge skill that tries to do everything.

Raul organized what he had at the office in the two cards below.