AI is strongest where the work already happens. That’s exactly why this announcement from Microsoft Build 2026 is more interesting than it first looks: Claude is now a selectable AI inside Excel Agent Mode — the tool an estimated 750 million people open every day.
What’s new
On June 8, Microsoft announced that Anthropic’s Claude is now an option in Excel’s Agent Mode. You can invoke Claude directly in the sheet: write and explain formulas, clean and transform messy data, generate a written analysis of what a sheet actually shows, and build automated workflows — without ever leaving Excel.
That’s more than a checkbox in a menu. Anyone who works with spreadsheets knows the constant context switch between data and a chat window. Microsoft is removing that break here.
Not just Excel: Claude in Foundry
Claude is also expanding deeper into the Microsoft stack. Claude Sonnet 4.5, Haiku 4.5, and Opus 4.1 are available in public preview in Microsoft Foundry — deployable through Foundry’s APIs, with Entra authentication, Azure billing, and SDKs for Python, TypeScript, and C#. The new Opus 4.8 has now landed in Foundry too. And agents built with the Claude Agent SDK can be dropped into Microsoft’s agent framework as named participants.
My take
The interesting part is the double role Microsoft is playing. On one hand, it’s pulling Claude deep into its most important products — Excel, Microsoft 365, Foundry. On the other, it’s pushing its own MAI models as competition. Microsoft clearly wants both: offer the best available AI, and avoid depending on a single provider.
For us as users, that’s good news for now. If I can choose between models inside Excel, the one that solves the task best wins. And having Claude right there in a spreadsheet you’ve known for twenty years lowers the barrier enormously — no new app, no new window, just there where the work is.
Sources: TechTimes, A Guide to Cloud, Microsoft Foundry Blog