Microsoft Agent Builder

Deep Dive: Microsoft Agent Builder

Microsoft Agent Builder is the no-code feature inside Microsoft 365 Copilot that lets any business user create custom declarative agents directly from the Copilot app toolbar. The user describes the agent in plain language — name, behavior, instructions — and attaches knowledge sources such as SharePoint libraries, Outlook mail, Teams channels, or PDF and Word files dragged into the prompt (drag-and-drop uploads arrived at Build 2025). The finished agent runs inside Microsoft 365 Copilot on desktop and web; there is no mobile version. For licensed users, internal conversations with such agents are included in the seat price and consume no Copilot Credits. A concrete case: an HR team points an agent at 45 onboarding PDFs in SharePoint, and every employee with a Microsoft 365 Copilot license (roughly $21–$30 per user per month) can query it without extra credit cost — the same question through Copilot Studio's pay-as-you-go rate would burn credits at $0.01 each. The boundary to Microsoft Copilot Studio is scope: Agent Builder covers lightweight knowledge agents, while Copilot Studio is the enterprise platform with Actions, external connectors, multichannel deployment and consumption billing (in Copilot Credits since 1 September 2025, $200 per 25,000-credit pack). Since Ignite in November 2025 an agent built in Agent Builder can be copied into Copilot Studio and extended there without a rebuild; since July 2026 every Copilot Studio agent automatically receives a Microsoft Entra Agent ID.