TL;DR: For 2026 office productivity, don’t pick “the best Excel assistant.” Pick the stack that matches your workflow: in-app agents for single-tool tasks, MCP + connectors for cross-tool work, and a governed file workspace with scoped access + version history when multiple agents must collaborate safely. Claude inside Excel is real now. On May 7, Anthropic moved Claude for Excel (plus Word and PowerPoint) into general availability for paid plans—an explicit bet that “AI in Office” will be experienced as a sidebar where work already happens ( Anthropic’s “Use Claude for Excel” (2026) ). If you live in spreadsheets all day, that’s not a small upgrade. But here’s the uncomfortable question: do knowledge workers actually live in Excel? Most don’t. They live in the gaps between tools .…