Microsoft on September 25 announced a .NET SDK for AG-UI (Agent-User Interaction). Created in collaboration with CopilotKit, the new SDK allows C# developers to work with the protocol that standardizes how agents communicate with user-facing applications.
The .NET SDK for AG-UI lives in the AG-UI repository alongside the TypeScript and Python SDKs, and is published on NuGet under the MIT license. Its C# implementation of AG-UI is usable from any .NET service, Microsoft said. AG-UI support for .NET in the Microsoft Agent Framework (MAF) is now based on the .NET SDK for AG-UI, the company added.
AG-UI is an event-based protocol that allows AI agents to interact with front-end applications. A back end emits AG-UI events natively, and a client consumes them from an agent written in any supported language. The protocol includes events in eight different categories, according to the documentation:
The .NET SDK for AG-UI works in both directions, Microsoft said. AGUI.Server turns an agent into an AG-UI endpoint and AGUI.Client enables a .NET application to consume an AG-UI endpoint.AGUI.Server and AGUI.Client are built on a common set of AG-UI primitives.
The .NET SDK for AG-UI ships as five packages on NuGet:
AGUI.Abstractions — protocol events, messages, tools, capabilities, and JSON serialization. AGUI.Formatting — event stream formatter abstractions and Server-Sent Events support. AGUI.Protobuf — protobuf codec and binary event stream formatting. AGUI.Client — AG-UI HTTP client and IChatClient integration. AGUI.Server — server-side adapter from ChatResponseUpdate streams to AG-UI events.
Microsoft offered the following links for getting started:
The company welcomes questions and feedback about the SDK in the AG-UI repository. It asks that questions about Microsoft Agent Framework integration be directed to the Microsoft Agent Framework discussion boards.