![(Updated) Microsoft 365 Copilot: Declarative agents model upgrade to GPT-5.1 [MC1194070]](https://mwpro.co.uk/wp-content/uploads/2025/06/pexels-alfonso-escalante-1319242-2533092-1024x683.webp "(Updated) Microsoft 365 Copilot: Declarative agents model upgrade to GPT-5.1 [MC1194070] 1")
Updated January 15, 2026: We have updated the timeline. Thank you for your patience.
[Introduction]
Microsoft 365 Copilot declarative agents are upgrading to the GPT-5.1 model, which uses an “auto” architecture. The orchestrator will automatically select the best model for each scenario, either the fast “chat” model or the advanced reasoning model, based on the user prompt.
[When this will happen]General Availability (Worldwide): Rollout will begin mid-January 2026 (previously early January) and is expected to complete by end of January 2026 (previously mid-January).
[How this affects your organization]Who is affected: All tenants using Microsoft 365 Copilot declarative agents.
What will happen:
- Declarative agents will upgrade to GPT-5.1.
- The advanced reasoning model will be available for complex queries.
- No admin configuration changes are required.
- Feature will be enabled by default for all applicable tenants.
No action is required.
[Compliance considerations]No compliance considerations identified. Review as appropriate for your organization.
Source: Microsoft
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