Claude arrives at Microsoft Foundry and 365 Copilot | Keryc
Today Microsoft and Anthropic expand their partnership: the Claude models Sonnet 4.5, Haiku 4.5 and Opus 4.1 are available in public preview in Microsoft Foundry and appear as an option in Microsoft 365 Copilot. What does this mean for companies, developers and users who already live in the Microsoft ecosystem? Let’s break it down.
What changes for companies and developers
Claude in Foundry lets you deploy models at scale with a serverless approach while Anthropic handles the infrastructure. That means you can start building without waiting months of paperwork or complex integrations.
Immediate deployment using Foundry APIs, tools and workflows.
Integrated billing: Claude is eligible for MACC and works with Azure agreements and billing, avoiding separate contracts and payment systems.
SDKs and authentication: access from Python, TypeScript and C# with Microsoft Entra.
In practice: if your team already uses Azure, you can now add Anthropic models without negotiating another vendor or setting up new billing. Less friction, fewer weeks lost to procurement.
Which models are available and when to use them
Anthropic offers three models with different goals. Not every model fits every job, and choosing well saves you time and money.
Sonnet 4.5: a model for coding and complex agents. Ideal when you need sophisticated reasoning, multi-step flows and autonomous programming tasks.
Haiku 4.5: the fastest and most economical, with performance near the frontier at about a third of Sonnet’s cost. Use it in high-volume apps like real-time assistance, moderation or sub-agents.
Opus 4.1: designed for specialized reasoning and problems that require sustained focus and precision.
All models in Foundry support Claude platform capabilities like code execution, web search and fetch, citation handling, vision, tool use and prompt caching. That makes it easier to build agents that combine several skills.
Claude inside Microsoft 365 Copilot and Excel
Claude already powers the Researcher agent in Copilot for complex research tasks and lets you develop custom agents in Copilot Studio. Also, Agent Mode in Excel now includes a preview option to use Claude.
Can you imagine asking Claude to find errors in a spreadsheet, generate formulas and iterate until the numbers balance? That’s exactly what this enables: generating formulas, analyzing data, spotting mistakes and refining solutions without leaving Excel.
A practical example: a financial analyst can ask Claude to turn a messy expense table into a report with corrected formulas and presentation-ready charts. It saves time and reduces manual errors.
Why it matters and what you should check before adopting
This integration lowers contractual and technical barriers, but it doesn’t remove important decisions. Before you integrate Claude in production, check:
Governance and compliance: make sure data policies, access controls and regulatory requirements are covered.
Data residency: Global Standard deployment is available and US DataZone is coming soon. Verify residency requirements.
Costs and architecture: pick the model that balances cost and accuracy. Try Haiku for volume and Sonnet for mission-critical tasks.
Testing and sandboxing: validate behavior in real scenarios and create automated tests to avoid unexpected results.
Practical perspective
If you already use Azure and Microsoft 365, this integration is an invitation to experiment without the weight of new contracts. For developers it’s an opportunity to integrate a coding agent like Claude Code directly into Foundry workflows. For business teams, it’s a way to bring advanced AI into everyday tools like Excel.
The news isn’t just about technical power, it’s about institutional ergonomics: less paperwork, faster deployments and more options to pick the right model for the use case.
Think of this as a new tool in your toolbox: useful, but it needs tests, rules and training to get the most out of it.
