Kesslernity · M365 Copilot Field Guide
Copilot Cowork
Research. Plan. Execute. With your approval.
Cowork is the agentic execution layer in M365 Copilot. You describe an outcome — Cowork searches your M365 data, breaks the task into steps, and takes action with your explicit approval before anything is sent, scheduled, or changed.
Status Frontier Preview
Updated May 2026
Access m365.cloud.microsoft
Built on Anthropic Claude
Published by kesslernity.com
Requires before you start

Microsoft 365 Copilot add-on licence (requires M365 E3 or E5 base) plus Frontier programme enrolment. Frontier is free but requires a separate opt-in at m365.cloud.microsoft → Settings → Frontier. Without Frontier enrolment, Cowork is not visible.
EU / EFTA / UK tenants only: Anthropic is disabled by default. Admin must enable it at admin.microsoft.com → Copilot → Settings → AI providers before Cowork works for any user in the tenant.

At a glance
What it is
An AI agent that takes action inside M365 —
sends emails, posts to Teams, creates calendar blocks.
Key difference from Chat
Chat drafts — you implement.
Cowork executes — with your approval at each action.
Built on
Anthropic Claude agentic model,
wrapped in Microsoft enterprise governance.
Use caseWhat you describeFor
Meeting follow-upFind my Teams transcript, draft and send the follow-up email to all attendeesAnyone who runs meetings
Weekly status postEvery Friday, pull my project emails, draft the Teams update, post after I approveProject manager · Team lead
Focus time protectionFind gaps in my next 5 days, propose 90-min focus blocks, create them after I confirmAnyone in back-to-back meetings
Commitment trackingFind every "I'll send / I'll follow up" in my emails from the last 14 days, flag overdueAccount manager · Consultant
Conflict resolutionFind calendar conflicts next 7 days, propose resolutions, reschedule after I approve eachManager · Executive
Renewal outreachSearch my history with [contact], draft a brief personalised email, send after I approveAccount manager · Customer success
Aspect Copilot Chat Copilot Cowork
Output A draft or answer — you decide what to do with it An action taken — email sent, event created, post published
Execution You read, copy, paste, act manually Cowork executes; pauses for your approval at each step
Time span Single response, immediate Multi-step, runs over minutes with checkpoints
Steering Static response; you decide next turn You can interrupt, redirect, pause, or cancel mid-task
Scheduled tasks Not available Up to 5 recurring prompts that run on a schedule
Custom skills Not available Up to 50 saved instruction sets, auto-loaded per conversation
1
Verify your licence
Confirm you have the M365 Copilot add-on assigned (requires M365 E3 or E5 base). Check under portal.microsoft.com → Licences. Without this licence, Cowork is not accessible.
2
Enrol in Frontier
Go to m365.cloud.microsoft → Sign in → Open Settings (top right) → Frontier → toggle on. Frontier is a free early-access programme. Cowork is only visible after enrolment.
3
Open Cowork
After Frontier enrolment, Cowork appears in the left sidebar at m365.cloud.microsoft. Select it. The interface shows a chat input and a Tasks panel on the right.
4
Describe your first task
Type a task outcome in plain language — not a question, a delegation. "Find every unresponded email from this week and draft replies for each" is better than "Can you help me with emails?" See the Delegation Brief format below.
The Delegation Brief format
Structure every Cowork prompt with these 4 parts
Part 1
Goal
The outcome you want — not the steps. State what done looks like, not how to get there. "Send a follow-up email to all attendees" is a goal. "Search Teams, then draft an email, then send it" is steps — Cowork works those out itself.
Part 2
Inputs
Which M365 sources to pull from. Name them explicitly: Outlook, Teams, Calendar, SharePoint folder, specific meeting transcript. Cowork can infer, but named sources produce fewer errors than "look at everything."
Part 3
Output
What to produce and in what format. "A Teams post in bullet format" is different from "a formal email under 150 words." The more specific the output description, the less iteration you need on the draft.
Part 4
Boundaries
What Cowork must NOT do without your explicit approval. "Show me the draft before sending." "Do not create any calendar event until I confirm the full list." "Do not contact anyone outside my organisation." These are the lines that prevent surprises.
Example — meeting follow-up
Goal: Send a follow-up email after my last meeting.

Inputs: Find the Teams transcript or my notes from the last 2 hours.

Step 1: Extract action items (what, owner, deadline), decisions made, and open
questions. Show me this list and wait for my confirmation before proceeding.

Step 2: Draft a follow-up email to all attendees with the above structure.

Step 3: Show me the full draft and the complete recipient list. Wait for my
explicit approval.

Step 4: Send only after I approve.
Email & messaging
  • Draft and send emails
  • Reply to and forward emails
  • Post to Teams channels
  • Send Teams direct messages
  • Draft messages for your approval
Calendar & scheduling
  • Create calendar events
  • Add attendees to meetings
  • Block focus time
  • Reschedule events
  • Find free slots across attendees
Documents & files
  • Create Word, Excel, PowerPoint
  • Generate reports and summaries
  • Browse SharePoint and OneDrive
  • Read and analyse file content
  • Share documents with named users
Research & analysis
  • Search across all M365 data
  • Read meeting transcripts
  • Synthesise from email threads
  • Deep Research across enterprise
  • Daily and weekly briefings
What it cannot do
  • Delete files or folders
  • Create Loop pages
  • Upload files to Teams
  • Access local device files
  • Access systems outside M365
  • Read encrypted files
  • Process files over 200 MB
Plugins (May 2026)
  • HubSpot
  • Notion
  • Miro
  • monday.com
  • Dynamics 365
  • Power BI
  • Custom plugins (org-built)
Scheduled prompts & custom skills
The two features that make Cowork a system, not a tool
01
Monday week-start briefing
Calendar, email priorities, and commitments due this week — before the day starts.
Highest priority
02
Weekly commitment tracker
Every "I'll send / I'll follow up" from the last 14 days, sorted by age, flagged if overdue.
High priority
03
Daily inbox priority scan
Top 5 emails needing action today, with a one-line "why this matters" per email.
Medium priority
04
Project status digest
Weekly summary from a specific project's emails, Teams, and calendar — posted to Teams channel.
Medium priority
05
Friday end-of-week digest
What was completed, what is pending, what needs attention Monday.
Optional

How to create a scheduled prompt: Describe the task to Cowork and include a time — "every Monday at 7 AM" or "every Friday at 4 PM." Cowork will propose the schedule and ask you to activate it. Manage existing schedules under Tasks → Scheduled tab. Each scheduled run still requires your approval before Cowork acts.

How skills work

A skill is a saved instruction set — a SKILL.md file stored in your OneDrive. Cowork reads all your skills at the start of every conversation and knows to use them when a matching task comes up.

Limit: Up to 50 skills per user.

Storage path:
/Documents/Cowork/skills/{skill-name}/SKILL.md

Create a subfolder per skill, then create SKILL.md inside it. You can also add up to 20 companion files per skill (templates, reference docs) — stored in the same folder.

Updating a skill: Open the SKILL.md file in OneDrive and edit it directly. Changes take effect at the next conversation. Or ask Cowork to update the skill during a conversation — it will modify the file if you confirm.

SKILL.md format
---
name: Weekly Project Update
description: Posts a structured weekly
  update to a Teams channel from
  the last 7 days of project emails
  and Teams messages.
---

# Instructions below

Every Friday at 4 PM, search emails
and Teams from the last 7 days for
[project name].

Draft a Teams post:
- ✅ Done this week
- 🔄 In progress
- 🚫 Blocked (with owner)
- 📅 Next week

Show me the draft. Wait for approval.
Post only after I confirm.

Cowork reads from your M365 environment — email, Teams, calendar, files. It does not access systems outside M365, cannot read locally stored files, and cannot retrieve information from the internet.

Outlook email — inbox, sent, search
Outlook calendar — events, availability, invites
Teams channels & chats — read and post
Meeting transcripts — via Teams recording
SharePoint files — documents, folders
OneDrive files — personal and shared
Dynamics 365 — rolling out 2026
Power BI dashboards — coming soon
Local device files — not accessible
Internet / web search — not accessible
SAP · Primavera · external ERP — not accessible (custom plugins can bridge this)
Encrypted files — not readable even with access
Available now
In pipeline
Not accessible
Low risk
Reading emails, searching Teams, browsing files, drafting content for review — no approval required.
Medium risk
Creating calendar events, creating documents, posting to Teams — shows approval dialog with preview.
High risk
Sending emails, modifying shared files, rescheduling others' meetings — shows approval dialog with prominent risk indicator.
EU / EFTA / UK tenants — action required before Cowork works

Cowork is built on Anthropic's Claude model, which operates as a Microsoft subprocessor. In EU, EFTA, and UK tenants, Anthropic is disabled by default because data may be processed outside the EU Data Boundary.

To enable: admin.microsoft.com → Copilot → Settings → View All → AI providers operating as Microsoft subprocessors → Anthropic → Enable. This requires an admin to explicitly acknowledge that data will leave the EU Data Boundary. Users cannot enable this themselves — it requires tenant-level admin action.

Cowork searches the wrong time window. Without a time boundary in your prompt, Cowork may pull from too broad a range (months of email instead of the last 7 days). Always state the window explicitly: "from the last 14 days," "since Monday," "from this week's meetings only."

The draft email includes the wrong recipients. Cowork infers recipients from context — which can produce unexpected results if a contact has multiple email addresses or if CC patterns from old threads are picked up. Always review the full recipient list before approving send.

A scheduled prompt fails silently. If a scheduled prompt encounters an error (no transcript found, a Teams channel permission changed), it may produce an empty or partial result without a visible error message. Check the Tasks panel for run history if a scheduled prompt seems to have not executed.

A custom skill is not applied to the task. Skills are matched by description at the start of the conversation. If the skill description is too vague, Cowork may not recognise that it applies. Write skill descriptions as specific outcome statements: "Generates the weekly HSE summary report for a named project from the last 7 days of incident data" rather than "weekly report."

Cowork cannot find the meeting transcript. Transcripts require Teams Meeting Recording to be enabled and the meeting to have ended. If the recording was off, or if the meeting was outside Teams, there is no transcript for Cowork to read. In that case, paste your own notes directly into the prompt.