Microsoft releases .NET SDK for AG-UI agent-user interaction protocol

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:

• Life-cycle events monitor the progression of agent runs.
• Text message events handle streaming textual content.
• Tool call events manage tool executions by agents.
• State management events synchronize state between agents and UI.
• Activity events represent ongoing activity progress.
• Subagent events track subagents and attribute their output.
• Special events support custom functionality.
• Draft events propose events under development. 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:
• AG-UI .NET SDK source and samples
• AG-UI documentation
• CopilotKit’s AG-UI .NET SDK post
• Agent Framework AG-UI documentation on Microsoft Learn
• Microsoft Agent Framework migration notes 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.