Microsoft added “Cowork” to the Frontier preview at the end of March 2026 after giving MVPs a sneak peak in Seattle the week before. I’ve been experimenting with it through our Microsoft 365 Copilot licences at work, as well as on my demo environment, both of which are enrolled in the Frontier programme, and while it’s early days, it’s already proving handy for a bunch of small but meaningful tasks and it’s been fun exploring some of the things it can do.
But, what I really really like about Cowork is the ability to create custom skills. These allow you to tweak the way the model work, enabling you customise how Cowork responds, acts and does tasks – this makes things really personal and interesting.
Note: Cowork cannot access local files, so any templates or files your skill references need to be in OneDrive or SharePoint.
What Cowork Does Out of the Box
Before you start looking at building custom skills, it helps to know what Cowork already brings to the table. At time of writing, you get 13 built in “skills”. These are Word, Excel, PowerPoint, PDF, Email, Scheduling, Calendar Management, Meetings, Daily Briefing, Enterprise Search, Communications, Deep Research and Adaptive Cards.
To use Cowork (I have a detailed walkthrough on this) you tell it what you want in plain English (just like a normal Copilot Prompt) and Cowork builds a plan, finds and loads the right skills and works through the steps. It shows its working as it goes and checks with you before doing anything irreversible like sending an email or posting to Teams. One important limitation is file access. Cowork currently only works with content in OneDrive and SharePoint. Local files are off limits by design in order to comply with Enterprise Data Protection and Privacy.
If you missed my earlier walk-through of Cowork and what it’s like to use day to day, you can find it here -> Copilot Cowork Walkthrough <-
What are Cowork Custom Skills
Microsoft’s initial built‑in skills cover plenty of ground, but they’re generic (I expect they will expand over time). Currently, they don’t know your templates, your style and preferences, your team’s habits or the workflows you have already defined and refined over time. That’s exactly the gap custom skills fill that gap.
If this sounds a bit like custom agents in Copilot, then yes it does I agree. There are similarities but the difference is CoWork determines when to use CoWork skills rather than you having to call them explicitly.A custom skill gives Cowork extra context and instructions that sit alongside the defaults. Currently, each user is able to create up to 20 custom skills. The setup is intentionally simple – with each skill consisting of a Markdown file [MD] which needs to be stored in a specific folder in your OneDrive.
These can be created manually or via a prompt. Let’s look at both approaches.
How to Create custom Cowork skills
Each custom skill sits in its own subfolder under /Documents/Cowork/Skills/ in your OneDrive and is defined in a single SKILL.md file.
If you are familiar with GitHub Copilot agent skills or Claud skills, then the structure will feel familiar. These are a YAML frontmatter block followed by plain Markdown instructions.
Custom Skill MD File Structure
---
name: your-skill-name
description: Provide description of what the skill does, and when Cowork should use it.
---
## Your instructions go here in plain Markdown. Be as specific as you need to be.The name is a unique identifier, all lowercase with hyphens. The description is what CoWork uses to decide when to load the skill, so make it specific rather than clever. The rest of the file is where you put the actual instructions, and you can go into as much detail as you need.
The description you give the custom skill is important as this drives this selection. A vague description like “this does styling” is much less useful than something specific: “Generates consistently formatted branded Word documents. Use this when asked to create formal document, reports or handover notes that need to follow the standard company template.”
The more specific you are, the more reliably Cowork picks the right skill. See the example below.
Creating a Cowork Custom Skill
Here’s how to manually create your first (and second) Custom Skill.
1. Create the folder structure
In your OneDrive, navigate to the Documents folder and then create a folder called Cowork if it doesn’t already exist. Next inside that that create a folder called Skills. Finally, create a subfolder for your specific skill. The name you give this folder typically matches the name in your SKILL.md folder.
The resulting path should look like:
OneDrive/Documents/Cowork/Skills/your-skill-name/SKILL.md2. Write your SKILL.md
The Skill.md file needs to follow a standard approach as shown above.
Here’s an example of a skill for generating consistently formatted and branded Word documents from a standard template.
Important: The description you give the custom skill is important as this drives this selection. “Generates consistently formatted branded Word documents. Use this when asked to create formal document, reports or handover notes that need to follow the standard company template.” is a good description.
---
name: branded-document
description: Generates consistently formatted branded Word documents. Use this when asked to create formal documents, reports, or handover notes that need to follow the standard company template.
---
When asked to create a Word document, follow these conventions:
## Document Structure
- Always start with a title page including the doc title, author, UK date, and version
- Follow with a brief executive summary (2–3 sentences maximum) which provides clear purpose, scope and end goal.
- Use Heading 1 for major sections and Heading 2 for subsections
- End with a "Next Steps" or "Actions" section where appropriate
- Only write in UK English
- Explain any acronyms after the first use of it.
## Formatting
- Use the Standard body text style for all paragraph text
- Font family should be Aptos by default.
- Tables should use the Table Grid style with a shaded header row
- Code or command examples should use the Code style or a monospace font
## Tone
- Write in a professional but accessible tone - Use active voice where possible
- Avoid jargon unless document is explicitly technical and the audience is technical
The above is meant to be simple to show the approach to creating skills. It is worth spending time over these to ensure they are tailored for your need.
Note: You can also reference supplementary files from within a skill if you have reference material you want Cowork to use. You can reference these and include the files you refer to in the OneDrive folder or link to a URL or SharePoint site.
3. Save, and start a new Cowork chat.
That is it. Once you have finished, save the file to the OneDrive folder and Cowork discovers your new custom skills automatically at the start of each new conversation.
Note: Custom skills are not validated by Microsoft. By using custom skills you are extending CoWork’s behaviour - so and as with any agent or prompt you use, test and test before using them. You can remove a skill by simply removing the folder in OneDrive.
Creating a skill with prompt.
You can also create skills by simply asking Cowork to “create a skill” based on a process that you want to be able to invoke via simple key words. This works best at the end of an iterative process.
I simply asked “Create me a skill called GTM for this work we have done“.
For example you can create a process for how you want to complete customer meeting preparation or prepare for a one2one. You can include what assets you want to create, actions you want to take and styles or formats you want to use.
This is a really good way to learn more about creating skills, they are quite powerful and provide a solid way for you to become a Custom Skills Pro!
How Cowork Uses Skills
When you start a conversation, Cowork evaluates which skills are relevant and loads them, both built-in and custom.
Note: When you hit the / key, you’ll note you can see “skills” as well as files and people etc, but so far, I haven’t found a way to explicitly reference or call a skill other than the built in ones.
As you work, the Cowork side panel updates in real time to show which are active, so you can confirm your custom skill has loaded before work starts. You’ll also see it show the skills that are currently being used.
In the example below, I have asked Cowork to create me a word doc about a water park in Orlando. I then subsequently asked Cowork to apply my “corporate branding” which then reformatted it using my style defined in my custom skill. This uses a previous custom skill created.
Note: Currently, Cowork doesn’t seem to show me in the skills section that it is using my skill – even though it told me it did in the chat.
Conclusion
Cowork and Custom Skills are in early preview – so expect UI and behaviour changes based on user feedback. Microsoft do keep their documentation up to date so worth keeping an eye on their official docs – see below.
Custom skills in Copilot Cowork are surprisingly easy to set up and they work really really well in my initial testing. I love that there no registration process, no admin configuration or approval – these skills just seems to work.
I do wish there was a more visual way of seeing what skills you have and what Cowork is using – I have filed my feedback so hoping this comes soon!! 🙂
For more reading, the Microsoft Learn documentation has more information about this.
Leave a Reply