Exploring Microsoft Copilot Cowork

What if your AI assistant could do more than answer questions - what if it could actually do the work?

Most AI assistants stop at the chat box. You ask a question, you get an answer, and the rest is up to you. Microsoft Copilot Cowork goes a step further - it brings a working assistant into Microsoft 365 that can read your email, draft your decks, prepare you for your meetings, and follow your personal way of working. The part that makes this interesting is not the chat. It is the ability to act across your entire Microsoft 365 environment and a personal skill system that teaches Cowork how you work.

I have been using Copilot Cowork since it became available through the Frontier program, and what started as curiosity quickly turned into a shift in how I approach daily work. This post covers what Cowork is, how it works, how to get started, and why the personalization model - personal instructions, memory, and custom skills - is what sets it apart from other AI assistants.

What is Copilot Cowork?

Copilot Cowork is an agentic assistant embedded in Microsoft 365 Copilot. Unlike a standard prompt-and-response interaction where you ask a question and get an answer, Cowork takes a broader instruction, plans the steps, and executes them on your behalf. It acts across Microsoft Outlook, Microsoft Teams, Microsoft Word, Microsoft Excel, Microsoft PowerPoint, Microsoft SharePoint, and Microsoft OneDrive. Rather than just answering questions, it runs multi-step tasks.

The difference between Microsoft 365 Copilot and Cowork is intent. Copilot helps you complete a single action. Cowork takes a broader instruction and breaks it into steps. It works through them one by one and shows each step in the conversation so you can follow along, steer, or interrupt at any point.

Before Cowork takes an action on your behalf - such as sending an email, posting a Microsoft Teams message, or scheduling a meeting - it asks for your permission. Approval prompts include a risk level indicator so you can gauge the impact. You can approve the action once, approve and remember for similar actions in the current conversation, or reject it entirely.

Why Cowork matters

Cowork removes the manual stitching between tools. Instead of switching between Microsoft Outlook, Microsoft Teams, and Microsoft SharePoint to prepare for a customer meeting, you can ask Cowork to do all of it in one pass. Read the latest emails, pull the meeting transcript, summarize the file the customer shared, and draft the follow-up.

Before Cowork, preparing for a customer meeting meant opening five tabs and scanning threads. Then copying notes into a document and writing a summary. With Cowork, I describe what I need and it handles the coordination. The time saved is significant. But the consistency is what matters more - Cowork applies the same thoroughness to every meeting, every time. I do not forget to check the latest email thread or miss a file that was shared two weeks ago.

The real lift comes from personalization. Cowork remembers preferences across sessions and follows skills that you define yourself. A generic assistant produces generic output. A personalized assistant produces output that reflects your standards, your voice, and your way of working.

The model behind Cowork

Copilot Cowork is powered by Anthropic Claude models. Claude is well suited to agentic work - long context windows, structured tool use, and reliable instruction following make it a strong fit for multi-step tasks that span multiple Microsoft 365 services.

If Cowork ever feels slow or unresponsive, the model status is publicly available at status.anthropic.com . Worth checking before opening a support ticket.

Getting started with Cowork

Getting started with Copilot Cowork requires a few prerequisites and takes only a few minutes once they are in place. However, not all of those prerequisites are in your hands - a couple of them require tenant-level configuration, so you might need your administrator to enable them before you can proceed.

Prerequisites

Copilot Cowork requires the following to get started:

• Microsoft 365 Copilot license. Cowork is a Microsoft 365 Copilot capability - you need an active Copilot license assigned to your account before anything else applies.
• Frontier program membership. Copilot Cowork is currently available through the Frontier program , Microsoft’s early access channel for the latest AI innovations. Frontier is rolling out to Microsoft 365 plans with Copilot licenses in select markets and languages, starting with the United States and English.
• Anthropic enabled in tenant. Cowork uses Anthropic models as a subprocessor. Administrators need to ensure this is enabled for the organization.
• Browser, desktop, or mobile app. Cowork works in your browser at m365.cloud.microsoft , in Microsoft Outlook and Microsoft Teams, and in the Microsoft 365 Copilot desktop and mobile apps for Windows, Mac, iOS, and Android.
• Cowork enabled in Microsoft 365 Copilot. Sign in to Microsoft 365 Copilot and switch from Copilot to Cowork using the toggle on the Copilot page.

Starting your first conversation

Starting a conversation with Cowork is straightforward. Open the Cowork home page, and you see a set of suggested prompts - Catch me up, Organize my inbox, Organize my week, Prep for a meeting, Plan an event, Prepare for my 1:1, and Research a company. Select one to get started quickly, or type your own instruction in the chat input. You can enter up to 250,000 characters, so detailed instructions are encouraged.

You can also attach files to give Cowork extra context - drag and drop files onto the chat input, or use the attachment button to add work context from your organization, upload files from your device, or attach cloud files from Microsoft OneDrive, Microsoft SharePoint, or Microsoft Teams.

How Cowork works

Understanding how Cowork operates day to day comes down to three areas: the conversation model, the approval system, and the controls you have while it works.

The conversation model

After you send a message, Cowork begins processing your request and shows its work in real time. A thinking indicator appears while Cowork plans its approach. Skill messages show when a capability is loaded (such as “Preparing to compose emails”). Step-by-step updates describe what is happening at each stage. The response streams in as it is generated, so you do not have to wait for the entire result.

If you think of something else while Cowork is still working, you can send another message. It is queued automatically and processed in order. If your new message changes the direction of the task, Cowork adjusts its approach accordingly.

Approvals and safety

Cowork asks for your permission before taking sensitive actions. The approval dialog shows a preview of what Cowork plans to do - for some actions, a rich preview of the content appears (a draft email, a Microsoft Teams message, or a scheduled meeting). Approvals for medium and high-risk actions include a risk level indicator.

You have several options when an approval appears:

• Action button (for example, Send, Post, or Create) - allows Cowork to proceed with the action this one time
• Do not ask again - allows the action and skips future approval prompts for similar actions in the current conversation
• Approve All - when multiple approvals are pending, allows all of them to proceed at once
• Cancel - stops the action and Cowork moves on with the rest of your request

The side panel

The side panel is a collapsible sidebar on the right side of your conversation that provides a real-time overview of what is happening:

• Progress - a progress bar showing the percentage of tasks complete, plus a step-by-step log of what Cowork is doing
• Input folder - files you provided as context for the conversation
• Output folder - files Cowork created, each with download and preview buttons
• Skills - skills that Cowork loaded during the conversation, shown as chips
• Schedule - scheduled prompts you created, with options to edit, pause, resume, or delete them
• Permissions - actions you approved with “do not ask again,” so you can review your approval preferences

Controlling the conversation

Cowork provides controls to pause, resume, or stop work at any time. You can pause softly (Cowork finishes what it is currently doing, then pauses) or pause hard (Cowork pauses immediately, including mid-step). After pausing, select Resume to continue from where Cowork stopped. To stop entirely, select Cancel - this clears the current task so you can send a new message.

Built-in skills

Copilot Cowork comes with 12 built-in skills that cover the core Microsoft 365 productivity surface:

Cowork loads the relevant skills automatically based on your conversation. You do not call skills by name - you describe what you need, and Cowork matches your request to the skill that fits. When a new skill loads, a message appears in the conversation and the skill shows up in the side panel.

One thing that accelerated my understanding of Cowork was asking it to list the built-in skills and save the raw Markdown files to the output folder. Opening those files in Visual Studio Code gave me a clear view of how skills are structured - the frontmatter format, the instruction patterns, and the conventions Cowork follows internally. That is how I discovered the .claude and .copilot memory folders, the progress tracking pattern, and several other ideas that shaped how I write my own skills. If you want to learn how Cowork thinks, start by reading the skills it already has.

Custom skills - making Cowork yours

The built-in skills are strong, but they are generic by design. They cannot know your tone, your structure, or your terminology without being told. The moment your work has a recognizable style - a specific tone, a fixed document structure, a set of product names, a brand palette, an audience you write for repeatedly - the built-in skills cannot know any of that without being told.

Custom skills close that gap. They turn one-off instructions into permanent behavior.

How custom skills work

Cowork discovers custom skills from a specific folder in your Microsoft OneDrive. To create a custom skill, add a subfolder under /Documents/Cowork/Skills/ and place a SKILL.md file inside it. Cowork discovers your custom skills automatically at the start of each conversation. You can create up to 50 custom skills. Each SKILL.md file can be up to 1 MB, and each skill can include up to 20 companion files - such as reference documents and scripts - with a total of 10 MB per skill.

A skill is a Markdown file with a YAML frontmatter block containing a name and description, followed by instructions in plain Markdown. The description is what Cowork reads to decide whether the skill applies to a given request - it acts as a routing mechanism, not a summary for human readers.

Skill names should be descriptive and memorable. Nothing stops you from having a little fun with it - here is a custom skill I created to generate activity summaries for longer time periods:

---
name: i-know-what-you-did-last-summer
description: |
  Analyses emails, calendar events, meeting transcripts, and files
  from a specified time period and creates a comprehensive activity
  summary. Use when user asks "what did I work on last quarter",
  "summarize my activity for the past 3 months", "create an activity
  report", or "what have I been up to".
---

# Activity summary

Generate a comprehensive activity summary for the requested time period.

## Data sources

Collect information from the following sources:

1. Sent emails - extract key topics, recipients, and outcomes
2. Calendar events - meetings attended, organized, or declined
3. Meeting transcripts - action items and decisions
4. Files created or modified in OneDrive and SharePoint

## Output format

Structure the summary as a Word document with these sections:

- **Period** - the date range covered
- **Key themes** - 3-5 major topics or projects based on volume and recurrence
- **Meetings** - total count, top recurring meetings, and notable one-off sessions
- **Communications** - most frequent contacts and key email threads
- **Deliverables** - files created or significantly edited during the period
- **Timeline** - a week-by-week breakdown of major activities

Keep the tone factual and concise. Do not editorialize or interpret intent.

Save the document to the output folder.

Custom skill example: i-know-what-you-did-last-summer

The name makes people smile, but the skill is genuinely useful - especially when preparing for performance reviews, updating your manager, or just figuring out where the last quarter went.

In my experience, when a personal skill and a built-in skill cover the same area, Cowork tends to favor the personal skill.

Creating skills with Cowork itself

You do not need to write skill files by hand. Cowork has a built-in skill for creating and managing skills - tell it what you want a skill to do in natural language, and it drafts the SKILL.md file and saves it to your Microsoft OneDrive. A few useful prompts to explore the skill system (I cover the full workflow for creating, refining, and managing skills in my next post):

Show all skills

List all skills loaded in the current conversation, including built-in and custom skills

Explain the daily-briefing skill

Show what a specific skill does and how it works

What triggers the docx skill?

Show what makes Cowork load a specific skill for a given request

The value of personal skills

The value of custom skills compounds over time, in four ways:

• Consistency - every output reflects the same standards. Your emails, drafts, posts, and decks sound like you, not like a generic AI.
• Speed - you stop re-explaining the same rules on every request. A two-line ask produces a finished draft.
• Quality control - skills act as guardrails. They catch the mistakes you keep correcting manually and prevent them from happening again.
• Scale - a skill is a one-time investment. Once it exists, every future request benefits from it without extra work.

The mindset shift is to treat Cowork less as a chatbot and more as a colleague you are onboarding. Every time you find yourself correcting the same thing twice, that is a candidate for a new skill.

Beyond skills - personal instructions and memory

Custom skills are not the only personalization surface in Cowork. The /Documents/Cowork/ folder supports additional files that shape how Cowork behaves across all conversations:

• copilot-instructions.md sits at the root of the Cowork folder and acts as your global personal instructions - similar to a copilot-instructions.md in a Visual Studio Code workspace, but scoped to you rather than a project. This is where I define my role, working hours, default behaviors, priority accounts, and cross-cutting rules that apply regardless of which skill is active. It is the identity layer that every skill inherits from.

• Memory files live under .copilot/ and .claude/ subfolders. These locations are not arbitrary - they are defined by the built-in skills themselves. The daily-briefing skill reads from .copilot/briefing-memory.md, and the calendar-management skill reads from .claude/calendar-memory.md. Cowork maintains and updates these files over time based on your conversations. My .copilot/briefing-memory.md captures priority senders, watched channels, and briefing preferences. My .claude/calendar-memory.md stores scheduling policies, focus-time protection rules, and meeting priority overrides.

  Memory files are not skills - they are context that Cowork consults when planning actions, ensuring it remembers your preferences without you repeating them every conversation.

Together, these layers form a full personalization surface: personal instructions define who you are and how you work, memory files capture what Cowork has learned about your patterns, and skills define how specific tasks should be executed. Each layer serves a different purpose, and all three contribute to turning a generic agent into one that works the way you do.

You do not need to write these files from scratch. Cowork can analyze your existing patterns and draft them for you. A few prompts to get started:

Analyse my sent emails from the past month, identify my writing style, communication patterns, and frequently used phrases, and create a copilot-instructions.md that captures how I work. Save it to the output folder.

Draft personal instructions based on your communication patterns

Use the .copilot briefing-memory skill. Review my calendar and email for the past two weeks, identify who I communicate with most often, and create a briefing memory file with my priority senders and recurring meeting patterns. Save it to the output folder.

Create a briefing memory file with your priority senders and patterns

Use the .claude calendar-memory skill. Look at my calendar patterns, scheduling preferences, and focus-time habits, then create a calendar memory file that captures my scheduling policies and meeting priority overrides. Save it to the output folder.

Create a calendar memory file with your scheduling policies

Referencing the specific skill name (.copilot or .claude) in your prompt helps Cowork route the request to the right memory subsystem. Each of these prompts gives Cowork real data to work from, so the resulting files reflect how you actually work - not a generic template.

Considerations

A few things to keep in mind as Cowork continues to evolve:

• Copilot Cowork requires the Frontier program. Cowork is rolling out to Frontier early access for Microsoft 365 plans with Copilot licenses in select markets and languages. Features may change as Microsoft iterates.
• File access is scoped to Microsoft 365. Cowork works with content in Microsoft OneDrive and Microsoft SharePoint. Local files are off limits by design to comply with enterprise data protection and privacy requirements.
• Custom skills are personal, not shared. There is no built-in mechanism to share skills across a team or organization. Each user maintains their own skill library in their personal Microsoft OneDrive.
• Custom skills are not validated by Microsoft. Unlike the 12 built-in skills, custom skills are user-created. Cowork does not validate their quality or accuracy - the output depends entirely on how the skill is written.

Final thoughts

Copilot Cowork is most valuable when you stop treating it as a chatbot and start treating it as a teammate that learns how you work. The built-in skills give you a strong starting point. Personal instructions and memory files make it context-aware. Custom skills make it yours.

Start with one skill. writing-style is a good first skill - it captures how you write, the terms you use, and the structure you prefer, and every other skill benefits from it automatically. From there, build skills for the tasks you repeat most often and let the value compound.

In my next post, I go deeper into the skill format itself - the anatomy of a SKILL.md file, how to structure reference files, the progress tracking pattern, and the full journey from GitHub Copilot instruction files to Copilot Cowork skills.

Happy exploring!

–Jesper

Header image attribution: Image created with help from Microsoft Copilot