You’ve typed the same instructions into Claude at least 50 times. Here’s how I want you to write my newsletter. Here’s the format for my reports. Here’s the tone, the structure, the rules. Every single session.
Claude Cowork skills fix this. A skill is a single file that tells Claude exactly how to handle a specific workflow. Once it’s installed, Claude reads it automatically in every session. No re-explaining. No copy-pasting prompts. No wasted time.
This guide covers how to find and activate skills, how to stack them, how to update an existing skill using the built-in Skill Creator, and how to build a brand new skill from scratch with a real example.
What Are Claude Cowork Skills?
Claude Cowork skills are persistent instruction files that shape how Claude behaves in every session. Each skill is a plain text file (SKILL.md) that describes a specific workflow, format, or set of rules. When a skill is active, Claude reads it and applies those instructions automatically whenever the task is relevant.
The simplest way to think about it: a skill is a system prompt you only have to write once. Instead of re-prompting Claude every time you want a specific output format or workflow, the skill handles it permanently.
Skills are different from regular chat prompts in one key way: they’re persistent. You install a skill once, and it’s available in every conversation until you turn it off. They’re also updateable. You can refine a skill over time without starting over.
See also: Claude Cowork Projects
How to Access Claude Cowork Skills
There are three places to find and manage skills in Claude Cowork: through plugins, through the Customize menu, and through the examples panel. Skills only work in the Cowork desktop app, not on claude.ai.
Option 1: Via Plugins
Click the plus icon in the Cowork sidebar and go to Plugins. Each plugin includes one or more bundled skills. The default plugins (Data, Productivity, Marketing, Sales) come pre-loaded with skills for things like data validation, content creation, and task management.
Selecting a skill from a plugin activates it immediately and starts a guided prompt. This is the fastest way to try a skill for the first time without setting anything up.
Option 2: Via the Customize Menu
Click Customize in the Cowork sidebar, then go to the Skills tab. This is where you manage everything: your uploaded or created skills live under My Skills, and pre-built options are in the Examples section.
This is the main hub for skill management. From here you can turn skills on or off, edit them with Claude, download them, replace them with an updated version, or delete them.
Option 3: Built-In Background Skills
Some skills are baked into Cowork at the system level and run silently in the background. These handle common file types: creating or editing Word docs, Excel spreadsheets, PowerPoint presentations, and PDFs. You can’t see or edit these, but they activate automatically whenever you work with those file types.
The one built-in skill you can see (but not edit) is the Skill Creator. More on that shortly.
How to Turn Claude Cowork Skills On and Off
In the Customize > Skills panel, any skill that appears grayed out is currently inactive. To activate it, just click the toggle next to it. It moves to the top of the list and becomes available immediately.
When a skill is off, Claude doesn’t reference it at all, even if the task would normally match. Turning skills off is useful when you want to avoid conflicts between skills or when a skill is only relevant for a specific project.
The three-dot menu next to any skill gives you additional options: try it in chat, edit it, download it, replace it with a file, or delete it. For skills in the Examples section you also get ‘Try in chat,’ which opens a pre-filled chat prompt so you can test the skill immediately.
Stacking Multiple Skills at Once
Claude Cowork can use more than one skill at a time. When you run a task, Cowork looks at all your active skills and decides which ones apply based on what you’re asking. Multiple skills can run on the same task simultaneously.
A practical example: if you ask Claude to clean up data in an Excel file, it might automatically apply the built-in spreadsheet skill, a data validation skill from your Data plugin, and a data exploration skill. Each adds a layer of instructions on top of the others without you needing to specify which ones to use.
This stacking behavior is part of what makes skills more powerful than simple prompts. Instead of writing one massive prompt that tries to cover everything, you break your instructions into focused skills. Claude combines them as needed.
See also: Claude Cowork tutorial
See also: Claude Cowork tips and tricks
See also: Claude Cowork Excel guide
See also: Claude Cowork PowerPoint guide
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How to Update a Claude Cowork Skill
Skills aren’t static. As your workflows change, the skill should change with them. The built-in Skill Creator handles updates so you don’t have to manually edit the file.
To update an existing skill, go to Customize > Skills, find the skill you want to modify, click the three-dot menu, and choose Edit with Claude. This opens a chat session with the Skill Creator and your current skill already loaded.
Telling Claude What to Change
Be specific about what you want to add, remove, or adjust. It helps to tell Claude upfront that it should not make any changes until you’ve approved them. That keeps you in control of what gets updated.
For example: ‘Do not make any changes until I approve them. I want to add a fifth section to the email newsletter skill that highlights a community win from this week.’
Claude will propose the change, explain exactly what it plans to modify, and wait for your go-ahead before touching the file.
Reviewing and Applying the Update
Once you say go ahead, Claude runs through all the changes. When it’s done, it packages the updated skill and prompts you to install it. Click Copy to Your Skills and choose Upload and Replace to swap the old version with the new one.
The skill is updated immediately. No export/import cycle, no separate file editor, no re-uploading manually.
How to Create a Claude Cowork Skill from Scratch
The Skill Creator isn’t just for updates. It’s also the fastest way to build a new skill, even if you’ve never written one before. You describe what you want, Claude asks clarifying questions, writes a draft, tests it, and packages it for you.
Here’s the full process from a real example.
Step 1: Describe the Skill You Want
Start a chat in Cowork and tell Claude what you want the skill to do. You don’t need to be precise. A rough description is fine. The key is to give enough context for Claude to understand the workflow and ask the right follow-up questions.
Example prompt: ‘I want you to build out a new skill for running. I enjoy long distance running but really struggle with being consistent with my speed work week over week. The skill should log my runs when I put them into chat. If you don’t notice a 5 to 7 day period without a message, remind me I’m falling behind on training. Ask me as many questions as you want before we build the skill.’
Ending with ‘ask me as many questions as you want’ is one of the most useful things you can add. It gives Claude permission to dig into the details before writing anything.
Step 2: Answer Claude’s Questions
Claude will come back with a structured list of clarifying questions. For a running skill, those questions covered things like: What counts as speed work for you? What’s your target frequency? Do you want the log saved as a CSV? Should the reminder be passive (only when you message) or proactive (scheduled)?
The more specific your answers, the better the first draft. Answer each question directly. If you’re unsure, say so and Claude will suggest a default.
Step 3: Review the Eval Results
After building the skill, Claude runs a quick evaluation: a set of test prompts that simulate real usage. You see two columns: what the output looks like with the skill active, and what it looks like without it.
For the running skill, the tests included: logging a regular run, logging a track session with intervals, and requesting a weekly summary. The with-skill version produced a structured log entry with pace, type, and notes. The without-skill version returned a flat text response with no tracking structure.
Pass rate for the with-skill version came back at 100% vs 56% without. That gap tells you the skill is doing something meaningful, not just adding noise.
Step 4: Install the Skill
Once the eval looks good, Claude packages the skill and prompts you to install it. Click Copy to Your Skills (or the equivalent install button shown). The skill appears immediately in your My Skills section.
From that point on, every time you mention a run, Claude picks up the skill automatically and logs it in the format you defined. No prompting required.
Built-In Skills in Claude Cowork
Not all skills are user-managed. Cowork ships with a set of built-in skills that run automatically and can’t be edited or viewed. These cover the most common productivity file types.
- Word documents (.docx) — formatting, templates, structured reports
- Excel spreadsheets (.xlsx) — formulas, charts, data analysis
- PowerPoint presentations (.pptx) — slide layouts, design consistency
- PDFs (.pdf) — reading, filling forms, combining documents
These built-in skills are why Cowork handles these file types so well out of the box. When you ask Claude to create an Excel report, it’s not improvising. It’s following a set of tested instructions.
The Skill Creator is also built-in, but unlike the file-type skills, you can see it (it shows up in your Examples section). You just can’t edit it. It’s the tool you use to build everything else.
See also: Claude Cowork Dispatch
What’s Inside a Claude Skill File
Every skill is a folder. When you download a skill from Cowork or build one outside the app, you get a folder with a specific structure. Understanding that structure helps you know what to look at when something isn’t working or when you want to make a change manually.
The Folder Structure
A skill folder contains one required file and up to three optional subfolders:
- SKILL.md (required) — the main instruction file. Contains YAML frontmatter at the top and the actual skill instructions in Markdown below it.
- scripts/ (optional) — executable code the skill can run, like Python scripts, Bash commands, or validation tools.
- references/ (optional) — documentation or reference material Claude loads only when needed. Useful for long guides or API docs you don’t want in context all the time.
- assets/ (optional) — templates, fonts, logos, or other static files used to produce output.
When you package a skill for sharing, all of this gets zipped into a .skill file. On the receiving end, the person uploads it through Customize > Skills.
The SKILL.md Frontmatter
The YAML frontmatter at the top of SKILL.md is the most important part. It controls when the skill triggers. Claude reads every skill’s frontmatter on every session, but only loads the full SKILL.md body if the frontmatter suggests the skill is relevant.
The two required fields are name and description. Name must be in kebab-case (words separated by hyphens, no capitals). Description must explain both what the skill does and when to use it, in under 1,024 characters.
A good description includes specific trigger phrases: ‘Use when user says write my newsletter, draft the email, or paste a YouTube link alongside any mention of subscribers.’ Vague descriptions that just say ‘helps with projects’ don’t trigger reliably.
Two naming rules worth knowing: you can’t include ‘claude’ or ‘anthropic’ in a skill name (they’re reserved), and you can’t use XML angle brackets anywhere in the frontmatter (security restriction).
Progressive Disclosure: Why Skills Don’t Slow Claude Down
Skills use a three-level loading system to keep things efficient. The frontmatter is always in context. The full SKILL.md body only loads when Claude decides the skill is relevant to the current task. Files in the references/ and assets/ folders only load if Claude specifically needs them.
This means you can have 10 skills installed without all 10 being loaded into Claude’s context at once. Each skill only expands when it’s actually needed. That’s why stacking multiple skills doesn’t dramatically slow down responses.
Skills Are Portable
A skill built for Cowork works identically in Claude Code and the Claude API. The skill file format is the same across all three surfaces. If your team uses Claude Code for engineering work and Cowork for knowledge work, the same skill file works in both.
A Note on Skill Security
Skills run with the same level of access as Claude in your session. A skill can instruct Claude to read files, run code, make API calls, or use any connected service. That makes the source of a skill important.
Anthropic’s own documentation puts it plainly: only install skills from trusted sources, and audit the skill’s contents before use. A skill is a plain text file, so you can read exactly what it does before installing it.
If you’re downloading a skill from a public source, open the SKILL.md and read the instructions before clicking install. Look for anything that seems out of scope for what the skill claims to do.
Frequently Asked Questions About Claude Cowork Skills
What is the difference between a skill and a plugin in Claude Cowork?
A skill is a single instruction file for one specific workflow. A plugin is a bundle of skills combined with connectors and other tools. Plugins are installed as a package; skills can be installed one at a time. Most users start with skills and move to plugins once they want more pre-built functionality.
Can I use multiple skills at the same time in Claude Cowork?
Yes. Cowork automatically stacks skills when multiple ones are relevant to the same task. If you’re working with a spreadsheet and have both a data validation skill and an Excel skill active, both will apply. You don’t need to specify which ones to use.
Do Claude Cowork skills work on claude.ai?
No. Skills in the context of Cowork are only available in the Claude desktop app. The claude.ai web interface does not support Cowork skills. Make sure you’re using the desktop app if you want skill functionality.
How do I delete or disable a skill I no longer need?
Go to Customize > Skills, find the skill, and click the three-dot menu. You can turn it off with the toggle (it stays installed but inactive), or delete it entirely. If you might want it again later, turning it off is safer than deleting.
Can I share a skill with someone else?
Yes. Use the three-dot menu to download the skill as a .skill file. The other person can install it by going to Customize > Skills and uploading the file. Skills are just text files, so they’re easy to share, back up, or post publicly.
Start Building Your First Skill
The hardest part of using Claude Cowork skills is building the first one. After that, the pattern clicks and you start seeing skills everywhere. Your weekly report format. Your email tone guidelines. Your data cleaning checklist. Every repeated instruction becomes a candidate.
Start simple. Pick one workflow you re-explain to Claude regularly. Open the Skill Creator, describe it in a few sentences, answer the questions, and install what it builds. Refine it over time as your workflow evolves.
The goal is a version of Claude that already knows how you work before you type a single word.
- Open Claude Cowork desktop app
- Go to Customize > Skills
- Click Skill Creator in the Examples section
- Describe one workflow you repeat regularly
- Answer Claude’s clarifying questions
- Review the eval results and install the skill
