A skill is the difference between an AI agent that's smart in general and an AI agent that's useful at your job. This tutorial gets you from zero to your first working skill in under thirty minutes. No coding. No prerequisites beyond a Claude Cowork account and a workflow you do every week.
By the end, you'll have a skill the agent loads automatically every time you ask it to do that workflow — and the agent will sound like your team, follow your format, and skip the steps you don't need.
What you'll need
- A Claude account with Cowork enabled (Pro plan or above as of 2026)
- One workflow you do regularly that you'd like to automate
- Access to two or three example outputs from past work (drafts you wrote, reports you produced, emails you sent)
- 30 minutes
What a skill is, in one paragraph
A skill is a folder with a SKILL.md file inside it. The SKILL.md file describes what the skill does and how to do it, in plain English. You can include reference files (templates, examples, data) alongside the SKILL.md. When you ask Claude Cowork to do something matching the skill's description, Claude reads the SKILL.md and uses it to follow your team's process. That's the whole concept.
Step 1 — Pick the workflow (5 minutes)
Don't pick a complicated one for the first skill. Pick something you do every week or two, that has a recognizable right answer when it's done, and that involves reading something, deciding something, and writing something.
Good first skills people have built at Build An Agent Day:
- Draft a weekly customer status update from these three sources.
- Write the meeting recap email after a discovery call.
- Generate a one-page brief from any new whitepaper I drop in this folder.
- Score an inbound resume against this job description.
- Draft the social media post when I publish a new newsletter edition.
Pick one. Write it down in one sentence: when I [trigger], I want Claude to [action] using [inputs] and produce [output].
Step 2 — Gather the source material (5 minutes)
Open a new folder on your desktop. Call it whatever your skill does — weekly-status-update, meeting-recap, resume-screen. Inside it, put two or three real past examples of the output (with names redacted if needed), any template, checklist, or rubric you use today, and a note describing the format and tone in plain English.
You don't need to be exhaustive. Two examples and a one-paragraph description is enough for a first version.
Step 3 — Write the SKILL.md (10 minutes)
Create a file called SKILL.md inside the folder. Use this structure: a short YAML frontmatter (name and description), then sections for when to use the skill, what it does, the process steps, the output format, examples, things to avoid, and voice and style.
The description in the frontmatter is the most important line you'll write. Claude uses it to decide whether to load this skill at all. Be specific about the trigger language — common phrases users will say when they want this skill to run.
Aim for clarity, not cleverness. The agent reads English literally, so write what you actually mean.
Step 4 — Drop in the examples (2 minutes)
Inside your skill folder, create an examples subfolder. Drop in the two or three past outputs you gathered in Step 2. Name them clearly: example-1-good.md, example-2-good.md, example-3-bad.md if you want to show what not to do.
Step 5 — Install it in Cowork (3 minutes)
- Open the skills directory for your account. On macOS, it's typically ~/Library/Application Support/Claude/skills/. On Windows, it's %APPDATA%\Claude\skills\.
- Move your skill folder into that directory.
- Restart Claude Cowork (or trigger a reload from the settings menu).
- The skill should appear in your skills list. Confirm.
If your team uses a shared skills repository, the install step is whatever your IT team set up — usually a git pull into the same skills directory.
Step 6 — Test it on a real task (5 minutes)
Open a new conversation in Cowork. Say: I need a weekly customer status update for [customer name]. (Or whatever your skill's trigger is.)
Claude should automatically load your SKILL.md and follow it. Watch what it does. Three things to check:
- Did it trigger the skill at all? If not, your description in the frontmatter wasn't specific enough — refine the trigger language.
- Did it follow the process? If it skipped a step, make that step more explicit in the process section.
- Does the output match your examples? If the format drifted, add a more explicit format spec or strengthen the examples.
Edit the SKILL.md, save, restart, try again. Most skills go through three to five rounds of refinement before they're solid.
Step 7 — Improve over time (ongoing)
Every time the skill produces output that needed editing, ask yourself: what did I have to change, and how would I have told a new hire to avoid that mistake? Add that instruction to the skill. After a month of use, your skill will be sharper than the SOP document you'd have written from scratch — because it's been refined against real work, not imagined work.
This is the most underrated thing about skills: they get better as you use them. Vendor-built features don't. Yours does.
What good looks like
- A frontmatter description specific enough that Claude triggers it correctly 95 percent of the time
- Three to five concrete process steps, not vague gestures
- At least three real example outputs in the examples folder
- A short "things to avoid" section informed by real mistakes
- A "voice and style" section that reads like your team's actual language
Most professionals can build something that meets that bar inside a single afternoon. Build An Agent Day exists to make that afternoon a useful one — you bring the workflow, we walk you through every table.
Frequently asked questions
What is a skill in Claude Cowork?
A skill is a folder containing a SKILL.md file (and optional reference files) that teaches Claude how to do a specific task the way your team does it. Claude loads the skill automatically when the user's request matches the skill's description.
Do I need to know how to code to build a Claude skill?
No. SKILL.md is plain English with light Markdown formatting. Most professional users build their first skill in 20 to 30 minutes without writing a line of code.
Where are Claude Cowork skills stored?
On macOS, in ~/Library/Application Support/Claude/skills/. On Windows, in %APPDATA%\Claude\skills\. Teams typically version-control a shared skills folder in a Git repo and pull updates into the local directory.
Can I share a skill with my team?
Yes. Share the skill folder via a shared drive, a Git repository, or your company's internal skills marketplace. Anyone who installs it into their own skills directory will have it available in their Cowork.
How do skills compare to ChatGPT Custom GPTs?
Both let you add domain-specific instructions to an AI agent. Skills are file-based, version-controllable, and load on-demand based on the user's task. Custom GPTs are conversation-scoped and live inside the OpenAI ecosystem. Skills are better for power users; Custom GPTs are simpler for first-timers.
How long does it take to build a useful Claude skill?
A first version takes 20 to 30 minutes. A well-tuned, team-quality skill takes 3 to 5 rounds of refinement, usually spread over a week or two of real use.