As organizations around the world continue to bring more agents into production, there’s a growing demand for AI models that align with regional expectations around data handling and control. Microsoft Copilot Studio aims to meet this need by combining model flexibility with enterprise-grade governance, empowering teams to choose the best model for a given scenario while maintaining control over how and where data is processed.
Today, we’re expanding that choice with the addition of Mistral Medium 3.5 for agent building and orchestration. Medium 3.5 is currently available worldwide for customers in early release environments.
For organizations in the European Union (EU), this model has the added benefit of providing more flexibility in how their agents are powered, while keeping data processing in-region. It also helps these teams avoid the extra procurement overhead that can come with adding a new model provider.
Medium 3.5, per Mistral, was built for “long-horizon tasks, calling multiple tools reliably, and producing structured output that downstream code can consume.” Reasoning effort is configurable per request, so the same model can answer a quick chat reply—or, alternatively, work through a complex agentic run. You can read more about this model on Mistral’s blog.
Model access and admin controls
We’re rolling out Medium 3.5 for customers in early release environments. As an experimental model, we recommend using it in non-production scenarios while testing and evaluations are completed.
As with all external model providers in Copilot Studio, admins stay in control:
- Opt in via the Microsoft 365 admin center to allow the Mistral Medium 3.5 preview for your tenant.
- Enable external model providers in the Microsoft Power Platform admin center so makers in your selected environments can select Mistral Medium 3.5 in the Copilot Studio model picker.
Until both switches are on, the model will not appear to makers. This gives IT teams a structured path to pilot, evaluate, and expand usage on their terms.
Get started with Mistral Medium 3.5 in Copilot Studio
- Admins: Review the enablement guide and model provider terms, then complete the two-step opt-in.
- Makers: Once your admin has enabled access, open any agent in Copilot Studio and select Mistral Medium 3.5 (Experimental) from the model selector.
Bringing choice and control together
With Mistral Medium 3.5, Copilot Studio continues to expand the range of models available for agent development—while keeping orchestration, governance, and lifecycle management in one place.
The result: customers can choose the right model for each scenario, meet regional and compliance requirements, and scale agents confidently within a unified platform.
More choice. More control. One platform.
