Claude Skills for marketing: write your first skill

Most people who use Claude for marketing paste the same instructions into every chat: the brand voice, the ad rules, the report format. A skill holds them once, and Claude opens it by itself when the task needs it.

This guide is for marketers and business owners who use Claude, in the app or in Claude Code. It shows how to turn a repeated way of working into a skill. You will see how Claude picks a skill, write your first one for ad review, and leave with three ready marketing skills.

The common mistake

The first mistake is one huge instruction file per project, with every rule for every task. It fills the conversation on every message, even when you need half of it.

The second is a skill with a vague description such as “helps with marketing”. Claude cannot tell when to open it, so it either never runs or runs in the wrong place.

The big picture: three loading stages

Skills use what the standard calls progressive disclosure: Claude does not read everything up front.

1. Discovery: at the start it reads only each skill’s name and description. The specification puts that at about 100 tokens per skill.
2. Activation: when your request matches a description, it reads that skill’s full SKILL.md.
3. Execution: it follows the instructions, and opens a reference file or runs a script from the skill when the instructions say so.

That is why you can install twenty skills and only pay for their descriptions until one is used.

A kitchen comparison

A chef does not hold every recipe in mind all day. They know the recipe titles in the book and open a recipe when its dish is ordered.

If it needs a special sauce, they turn to the sauce page. The skill is the recipe, and its description is the title in the index.

The rule: the description decides when a skill opens, so write the what and the when.

Try it: how Claude picks a skill

In the first tab, pick a request and watch what Claude reads at each stage and how much enters the context. In the second, type your skill’s name and description; it checks them against the specification and builds the file for you to copy.

Anatomy of a skill

A skill is a folder with a required SKILL.md and optional files: references, templates and scripts. The file starts with a YAML block between two lines of dashes, followed by plain-language instructions.

Claude Code adds fields of its own. The most useful is disable-model-invocation: true, for a skill that only runs when you call it with /skill-name. Another is argument-hint, which hints what to type after the command.

Write your first skill: ad review before publishing

1. Create the folder

In Claude Code, put it in .claude/skills/ad-copy-review/ inside the project, or in ~/.claude/skills/ad-copy-review/ to use it in every project. When names collide, a personal skill wins over a project skill.

2. Write SKILL.md

---
name: ad-copy-review
description: Reviews ad copy before it goes live on Meta, TikTok or Snapchat, in Arabic or English. Checks the promise, clarity, claims that need proof and the brand voice. Use when the user asks to review an ad, a caption or campaign copy before publishing.
---

# Ad review

1. Read the ad copy; ask for the product page link if it is missing.
2. Compare the promise in the ad with what the product really does.
3. If you find a number, a guarantee, or a health or money promise,
   open references/claims.md and apply it.
4. Apply the voice rules in references/voice.md.
5. Return, in this order:
   - three issues, most important first
   - the fixed copy
   - one alternative headline
Never add numbers or results that are not in the copy or the page.

3. Add the reference files

references/voice.md holds your brand’s voice rules, and references/claims.md lists the claims that need proof before publishing. Claude reads neither until a step says so, so their length costs nothing on other requests.

4. Test the description, not the steps

Write three requests that should open the skill, such as “check this caption before I post it”, and two that should not. If it does not open when it should, the problem is the description, not the steps: add the words your team actually uses.

Where to use it

• Claude Code: the folder is enough. The skill runs when a request matches its description, or when you type /ad-copy-review.
• The Claude app: zip the folder, then go to Customize, then Skills, add a skill and upload it. Code execution and file creation must be turned on in settings, and the skill stays private until you share it.
• Other tools: skills are an open standard that Anthropic started and many coding tools support, so the same folder works outside Claude too.

Limits to know before you write

• Keep SKILL.md under 500 lines and move details into reference files one level below it.
• In Claude Code the description plus when_to_use is cut at 1,536 characters in the listing, so put the main use first.
• A skill can contain scripts that run on your machine. Do not install a skill from a source you do not know before reading its files, and check its allowed-tools.

Worth knowing

The open skills specification recommends keeping SKILL.md instructions under 5,000 tokens, because the whole file enters the context once the skill activates. References and scripts load only when needed, which is why long details belong there.

Source: the Agent Skills specification

Checklist before you rely on a skill

• The name uses lowercase letters and hyphens and matches the folder.
• The description says what and when, in words your team uses.
• Steps are numbered, one action per step.
• Long details live in reference files, not in SKILL.md.
• I tried five requests: three that should open it and two that should not.
• I read every script in any skill I did not write myself.

Your task

Pick a task you repeat every week and write a five-step skill for it with the builder above. Try it on three real requests, and share the description you settled on in the students’ space of the Evollo community.

Free resource

Three ready marketing skills in a ZIP: campaign brief, ad review with its two reference files, and a weekly report from an export. Upload them as they are, then edit the voice file with your brand’s rules.

Next step

If you build with a coding assistant such as Claude Code, read my free book What Vibe Coding Didn’t Tell You. It shows, through a practical story, how to make what you build hold up with your first customers. Read the book free.