Microsoft
The only one of the five that can already see your files. That changes what a good prompt looks like: less structure, more pointing.
How to prompt it
Use GCSE: Goal, Context, Source, Expectations. Microsoft states that only a clear goal is strictly required.
Write in flowing natural language. Skip the tags and headings you would use on an API model.
Name the source precisely — a specific file, channel, meeting or date range — not "our documents".
Refine in the same conversation instead of starting over; the assistant keeps the thread’s context.
Check what it cited. If it did not open the file you meant, the answer is ungrounded regardless of how confident it sounds.
Strengths
- Grounded in your own tenant — documents, mail, meetings and chats — which is the strongest defence against invented answers.
- Works inside the apps where the work already lives, so there is no copy-paste step.
- Microsoft publishes a plain-language prompt framework (GCSE) aimed at non-technical staff.
- Tenant data handling is governed by your existing Microsoft 365 agreements.
Weaknesses
- You do not choose the underlying model or its version, and behaviour can change without notice.
- Heavy XML or Markdown scaffolding is wasted here; the interface is built for natural language.
- Answer quality is capped by what the assistant is permitted to see — a Source it cannot reach is worse than no Source at all.
- Few of the API-level controls — verbosity, thinking depth, temperature — are exposed.
Models
Microsoft 365 Copilot
Assistant embedded across Word, Excel, Outlook, Teams and PowerPoint, grounded in your tenant’s content.
- Context
- —
- Max output
- —
Good for: Summarising meetings and threads, drafting from your own documents, and finding things across the tenant.
Watch out: Runs on models Microsoft selects. For reproducibility across versions, use an API model directly.
Sources and grounding
- 1Get started writing prompts in Microsoft 365 CopilotMicrosoft SupportThe GCSE parts, in Microsoft’s own words.
- 2The building blocks of a good Copilot prompt (PDF)MicrosoftMicrosoft-published one-page reference.