Microsoft Copilot Studio: Mistral Medium 3.5 will be available (admin opt-in required)

What and Why

Microsoft Copilot Studio is introducing support for Mistral Medium 3.5. This update will provide customers with more flexibility to select models that best meet their business needs for agent orchestration and generative AI scenarios. External models such as Mistral remain disabled by default and require admin opt-in, ensuring administrators maintain control over model usage, data access, and compliance.

Rollout Schedule

• Public Preview: Rollout begins at the end of May 2026.

Impact on Your Organization

Who is affected

• Admins managing Microsoft Copilot Studio
• Organizations building or managing agents in Microsoft Copilot Studio

Platforms/Services

• Microsoft Copilot Studio
• Microsoft admin center
• Power Platform admin center

What will happen

• Mistral Medium 3.5 will be available as a selectable model in Copilot Studio for supported environments.
• The model will be included in the multi-model selection experience for agent orchestration.
• External models, including Mistral, will be disabled by default.
• Admins will need to enable external models at the tenant level before use.
• Makers will be able to select Mistral Medium 3.5 after admin enablement.
• Existing policies and governance controls will continue to apply.
• There will be no impact to users or workflows unless admins enable external models.

Action Required / Recommendations

No action is required unless you plan to enable this feature.

If you choose to enable Mistral Medium 3.5:

• Review external model configuration in your tenant
  • Enable external models in the Microsoft admin center. Review: Connect to xAI's models | Microsoft Learn
• Configure permissions and governance in the Power Platform admin center. Review: Allow external language models for generative responses | Microsoft Learn
• Communicate this change to makers using Copilot Studio.
• Update internal governance or AI usage policies if applicable.

Learn more: 

• Connect to xAI's models | Microsoft 365 Copilot | Microsoft 365 | Microsoft Learn
  
• Allow external language models for generative responses | Microsoft Learn
  
• Mistral Medium 3.5 joins Copilot Studio model lineup for agents | Microsoft Copilot Blog
  
• Select a primary AI model for your agent | Microsoft Copilot Studio | Microsoft Learn
  

Compliance considerations

QuestionAnswerDoes the change introduce or significantly modify AI or ML capabilities that interact with or provide access to customer data?Yes. This change will introduce Mistral Medium 3.5 as an external model option for generative scenarios in Copilot Studio, expanding AI and ML capabilities that can interact with customer data when enabled by administrators.Does the change provide end users any new way of interacting with generative AI?Yes. This change will allow makers to select an additional third-party model, Mistral Medium 3.5, when building agents, providing a new option for generating AI responses.Does the change add any integration to third party software products, and if so what?Yes. This change will integrate Mistral as a third-party external model provider within Microsoft Copilot Studio.Does the change include an admin control and can it be controlled through Entra ID group membership?Yes. This change will include an admin-controlled opt-in setting at the tenant level to enable external models; however, control through Entra ID group membership is not specified.