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.NET: Add MCP Apps support to AG-UI (.NET) #5216

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Add MCP Apps sample with AG-UI integration; add comprehensive tests f…
halllo Apr 9, 2026
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Update README to specify AGUI_SERVER_URL for running the client
halllo Apr 11, 2026
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1 change: 1 addition & 0 deletions dotnet/Directory.Packages.props
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Expand Up @@ -106,6 +106,7 @@
<PackageVersion Include="A2A.AspNetCore" Version="0.3.4-preview" />
<!-- MCP -->
<PackageVersion Include="ModelContextProtocol" Version="1.1.0" />
<PackageVersion Include="ModelContextProtocol.AspNetCore" Version="1.1.0" />
<!-- Inference SDKs -->
<PackageVersion Include="AWSSDK.Extensions.Bedrock.MEAI" Version="4.0.5.1" />
<PackageVersion Include="Microsoft.ML.OnnxRuntimeGenAI" Version="0.10.0" />
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6 changes: 6 additions & 0 deletions dotnet/agent-framework-dotnet.slnx
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Expand Up @@ -114,6 +114,12 @@
<Project Path="samples/02-agents/AGUI/Step05_StateManagement/Client/Client.csproj" />
<Project Path="samples/02-agents/AGUI/Step05_StateManagement/Server/Server.csproj" />
</Folder>
<Folder Name="/Samples/02-agents/AGUI/Step06_McpApps/">
<Project Path="samples/02-agents/AGUI/Step06_McpApps/Client/Client.csproj" />
<Project Path="samples/02-agents/AGUI/Step06_McpApps/Server/Server.csproj" />
<Project Path="samples/02-agents/AGUI/Step06_McpApps/McpServer/McpServer.csproj" />
<Project Path="samples/02-agents/AGUI/Step06_McpApps/Tests/Tests.csproj" />
</Folder>
<Folder Name="/Samples/02-agents/DevUI/">
<File Path="samples/02-agents/DevUI/README.md" />
<Project Path="samples/02-agents/DevUI/DevUI_Step01_BasicUsage/DevUI_Step01_BasicUsage.csproj" />
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44 changes: 44 additions & 0 deletions dotnet/samples/02-agents/AGUI/README.md
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Expand Up @@ -199,6 +199,49 @@ cd Step05_StateManagement/Client
dotnet run
```

### Step06_McpApps

Demonstrates AG-UI integration with MCP Apps: HTML UI resources attached to MCP tools and delivered to capable AG-UI clients through the event stream.

If you are new to MCP Apps themselves, start with the official overview: [MCP Apps Overview](https://modelcontextprotocol.io/extensions/apps/overview).

This sample is more involved than the earlier getting-started samples because it includes three moving parts:

- An MCP server that exposes a `get-time` tool and a bundled HTML app resource
- An AG-UI server that attaches those MCP tools to an `AIAgent` and proxies MCP `resources/read` and `tools/call` requests
- A console client that shows the AG-UI protocol flow, including the `ACTIVITY_SNAPSHOT` event that carries the `ui://` resource URI

The browser-side MCP App, proxied request flow, event ordering, and conformance coverage are documented in the dedicated sample guide:

- [Step06_McpApps/README.md](Step06_McpApps/README.md)

Use that README when you want the full architecture, request and response examples, or the exact MCP App protocol details.

At a high level, `Step06_McpApps` demonstrates:

- Binding a tool to an MCP App resource via MCP metadata
- Returning `ACTIVITY_SNAPSHOT` events so a browser host can load the HTML app in-place
- Short-circuiting proxied MCP `resources/read` and `tools/call` requests on the same AG-UI endpoint instead of invoking the agent again
- Verifying the integration with sample-level conformance tests

**Run the sample:**

```bash
# Terminal 1
cd Step06_McpApps/McpServer
dotnet run

# Terminal 2
cd Step06_McpApps/Server
dotnet run

# Terminal 3
cd Step06_McpApps/Client
dotnet run
```

Try asking: "What time is it?"

## How AG-UI Works

### Server-Side
Expand Down Expand Up @@ -297,6 +340,7 @@ For the most up-to-date AG-UI features, see the [Python samples](../../../../pyt
### Related Documentation

- [AG-UI Overview](https://learn.microsoft.com/agent-framework/integrations/ag-ui/) - Complete AG-UI documentation
- [MCP Apps Overview](https://modelcontextprotocol.io/extensions/apps/overview) - Conceptual overview of MCP Apps, rendering model, and host responsibilities
- [Getting Started Tutorial](https://learn.microsoft.com/agent-framework/integrations/ag-ui/getting-started) - Step-by-step walkthrough
- [Backend Tool Rendering](https://learn.microsoft.com/agent-framework/integrations/ag-ui/backend-tool-rendering) - Function tools tutorial
- [Human-in-the-Loop](https://learn.microsoft.com/agent-framework/integrations/ag-ui/human-in-the-loop) - Approval workflows tutorial
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15 changes: 15 additions & 0 deletions dotnet/samples/02-agents/AGUI/Step06_McpApps/Client/Client.csproj
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@@ -0,0 +1,15 @@
<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFrameworks>net10.0</TargetFrameworks>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
</PropertyGroup>

<ItemGroup>
<ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
<ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.AGUI\Microsoft.Agents.AI.AGUI.csproj" />
</ItemGroup>

</Project>
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