Microsoft Copilot Cowork: A Practical Introduction

Post 1 of 14 — Series Opener

Introduction

Most people have spent the last two years using AI to help them work — drafting emails, summarising threads, sketching slides. Microsoft Copilot Cowork is a different kind of product. It does not assist with tasks; it carries them out. You describe an outcome, Cowork plans the steps, executes them across your Microsoft 365 environment, and asks for your approval before anything sensitive leaves your tenant. This series is a hands-on guide to what Cowork actually does today, what it requires, where the limits lie, and how to use it as a knowledge worker, an IT pro, or an admin.

What Cowork Actually Is

What Cowork is

Cowork is a cloud-hosted agentic orchestration layer embedded in your Microsoft 365 tenant. It runs inside Microsoft 365 Copilot — accessible at m365.cloud.microsoft, in Outlook and Teams, and in the Microsoft 365 Copilot desktop app for Windows and Mac. You describe a task in plain language, Cowork creates a plan, reasons across your calendar, email, files, and Teams content via Microsoft’s Work IQ layer, and produces a result. Approvals are required for sensitive actions (sending email, posting to Teams, scheduling meetings); progress is visible at every step; you can pause, resume, or cancel at any time.

Multi-model under the hood

Cowork uses Anthropic Claude alongside OpenAI models. Microsoft’s orchestration selects the appropriate model for each task. The Researcher agent’s Critique capability — where one model drafts and a second model from a different provider reviews — scores 57.4 on the DRACO benchmark, a 13.8% improvement over single-model approaches.

Where it lives

Cowork operates inside the Microsoft Enterprise Data Protection boundary. When Anthropic models are invoked, Anthropic acts as a Microsoft subprocessor under Microsoft’s Product Terms and Data Processing Addendum (in effect since 7 January 2026). This is materially different from standalone Claude Cowork, which processes data on Anthropic’s own infrastructure under Anthropic’s enterprise agreement.

Licensing and availability

Cowork is currently available through the Microsoft Frontier opt-in program. It is bundled with Microsoft 365 E7 — the new Frontier Suite tier that combines M365 E5, the Microsoft Entra Suite, M365 Copilot, and Agent 365. E7 became generally available on 1 May 2026 at $99 per user per month. General availability for Cowork itself does not yet have a firm public date.

Regional notes

Anthropic models are enabled by default for most commercial public-cloud tenants. Tenants in the EU, UK, and EFTA must explicitly opt in due to data residency constraints. Government, sovereign, GCC, GCC High, and DoD clouds do not have access; no toggle is shown.

Built-in skills

Cowork ships with 13 built-in skills today: Word, Excel, PowerPoint, PDF, Email, Scheduling, Calendar Management, Meetings, Daily Briefing, Enterprise Search, Communications, Deep Research, and Adaptive Cards. Each skill is a packaged capability that the agent loads on demand. You can also create up to 20 custom skills by placing SKILL.md files in your OneDrive /Documents/Cowork/Skills/ folder — Cowork discovers them automatically at the start of each conversation.

Hands-on parameters worth knowing

• Prompts can be up to 250,000 characters.
• Attached files must be under 200 MB.
• Cowork cannot access local files (OneDrive and SharePoint only), cannot delete OneDrive or SharePoint files, and cannot read encrypted files even when the user has access.
• Mobile is not yet supported (browser and desktop only).
• Custom skills are not validated by Microsoft — review their outputs.
• Real adopter signal. Capital Group — a global investment firm — is among the first enterprise adopters and describes Cowork as “taking real action, connecting steps, coordinating tasks, and following through across everyday workflows” while operating fully within the organization’s security and risk boundaries.

What This Series Will Cover

The next 13 posts go hands-on, one topic at a time:

1. Enabling Cowork (Frontier program, admin steps)
2. The Anthropic subprocessor and EU data residency
3. The 13 built-in skills, in detail
4. Custom skills with SKILL.md (the hands-on skills post)
5. The Email skill
6. Calendar Management and Scheduling skills
7. Meetings and Daily Briefing
8. Document creation (Word, Excel, PowerPoint, PDF)
9. Enterprise Search and Deep Research
10. Approvals, Pause/Resume, and the Tasks view
11. Work context — attaching files and grounding Cowork
12. Limits and known constraints (read this before you scale)
13. What’s next: E7, Agent 365, Researcher Critique

Takeaway

Cowork is the first Microsoft AI surface where the unit of output is a finished task, not a generated paragraph. Treat it as such: brief it well, approve carefully, audit honestly. The next 13 posts show you how, with no marketing varnish.

Sources

Cowork common questions (Frontier) Get started with Cowork Microsoft 365 E7 / Frontier Suite Anthropic as a subprocessor for Microsoft Online Services