Microsoft pushed Agent Mode in Word to general availability for all Microsoft 365 Copilot subscribers on April 22, 2026, and by mid-2026 made it the default experience across Word, Excel, and PowerPoint rather than an opt-in. It operationalizes multistep planning, tool use across the open document and referenced files, and persistent context, then reports back a summary of what it changed. Satya Nadella described the shift as moving from "AI that suggests things" to "AI that does things." Reviewing the full document after an Agent Mode pass, not just its summary, is the standard practical caution.