.NET: Use Responses API for hosted web search in AG-UI

dotnet/samples/05-end-to-end/AGUIClientServer/AGUIServer/AGUIServer.csproj

@@ -9,8 +9,8 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.AI.OpenAI" />
     <PackageReference Include="Azure.Identity" />
+    <PackageReference Include="OpenAI" />
   </ItemGroup>
 
   <ItemGroup>

dotnet/samples/05-end-to-end/AGUIClientServer/AGUIServer/Program.cs

@@ -1,13 +1,14 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using System.ClientModel.Primitives;
 using System.ComponentModel;
 using AGUIServer;
-using Azure.AI.OpenAI;
 using Azure.Identity;
 using Microsoft.Agents.AI.Hosting;
 using Microsoft.Agents.AI.Hosting.AGUI.AspNetCore;
 using Microsoft.Extensions.AI;
-using OpenAI.Chat;
+using OpenAI;
+using OpenAI.Responses;
 
 WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 builder.Services.AddHttpClient().AddLogging();
@@ -19,35 +20,15 @@
 
 const string AgentName = "AGUIAssistant";
 
-// Create the AI agent with tools
+// Create a Responses-backed OpenAI client that sends a bearer token to the Azure endpoint.
 // WARNING: DefaultAzureCredential is convenient for development but requires careful consideration in production.
 // In production, consider using a specific credential (e.g., ManagedIdentityCredential) to avoid
 // latency issues, unintended credential probing, and potential security risks from fallback mechanisms.
-var agent = new AzureOpenAIClient(
-        new Uri(endpoint),
-        new DefaultAzureCredential())
-    .GetChatClient(deploymentName)
-    .AsAIAgent(
-        name: AgentName,
-        tools: [
-            AIFunctionFactory.Create(
-                () => DateTimeOffset.UtcNow,
-                name: "get_current_time",
-                description: "Get the current UTC time."
-            ),
-            AIFunctionFactory.Create(
-                ([Description("The weather forecast request")]ServerWeatherForecastRequest request) => {
-                    return new ServerWeatherForecastResponse()
-                    {
-                        Summary = "Sunny",
-                        TemperatureC = 25,
-                        Date = request.Date
-                    };
-                },
-                name: "get_server_weather_forecast",
-                description: "Gets the forecast for a specific location and date",
-                AGUIServerSerializerContext.Default.Options)
-        ]);
+IChatClient chatClient = new OpenAIClient(
+        new BearerTokenPolicy(new DefaultAzureCredential(), "https://ai.azure.com/.default"),
+        new OpenAIClientOptions { Endpoint = new Uri(endpoint) })
+    .GetResponsesClient()
+    .AsIChatClientWithStoredOutputDisabled(model: deploymentName);
 
 // WARNING: When adding session persistence (e.g., WithInMemorySessionStore), or running in production,
 // make sure to also register an AgentIsolationKeyProvider to scope sessions by principal in multi-user
@@ -57,7 +38,26 @@
 // Register the agent with the host and configure it to use an in-memory session store
 // so that conversation state is maintained across requests. In production, you may want to use a persistent session store.
 builder
-    .AddAIAgent(AgentName, (_, _) => agent)
+    .AddAIAgent(AgentName, "You are a helpful assistant.", chatClient)
+    .WithAITools(
+        new HostedWebSearchTool(),
+        AIFunctionFactory.Create(
+            () => DateTimeOffset.UtcNow,
+            name: "get_current_time",
+            description: "Get the current UTC time."),
+        AIFunctionFactory.Create(
+            ([Description("The weather forecast request")] ServerWeatherForecastRequest request) =>
+            {
+                return new ServerWeatherForecastResponse()
+                {
+                    Summary = "Sunny",
+                    TemperatureC = 25,
+                    Date = request.Date
+                };
+            },
+            name: "get_server_weather_forecast",
+            description: "Gets the forecast for a specific location and date",
+            AGUIServerSerializerContext.Default.Options))
     .WithInMemorySessionStore();
 
 WebApplication app = builder.Build();

dotnet/samples/05-end-to-end/AGUIClientServer/README.md

@@ -18,11 +18,18 @@ The demonstration has two components:
 Configure the required Azure OpenAI environment variables:
 
 ```powershell
-$env:AZURE_OPENAI_ENDPOINT="<<your-model-endpoint>>"
+$env:AZURE_OPENAI_ENDPOINT="https://<your-resource>.openai.azure.com/openai/v1/"
 $env:AZURE_OPENAI_DEPLOYMENT_NAME="gpt-5.4-mini"
 ```
 
-> **Note:** This sample uses `DefaultAzureCredential` for authentication. Make sure you're authenticated with Azure (e.g., via `az login`, Visual Studio, or environment variables).
+> [!NOTE]
+> Include `/openai/v1/` in the endpoint. The OpenAI SDK uses `DefaultAzureCredential` to obtain a bearer token. Make sure you're authenticated with Azure, for example through `az login`, Visual Studio, or environment variables.
+
+> [!NOTE]
+> This sample calls Azure OpenAI inference directly through the resource endpoint. It does not require a Microsoft Foundry project. A project-scoped application would instead use a Foundry project endpoint with `Azure.AI.Projects` and the Agent Framework Foundry provider.
+
+> [!NOTE]
+> The server uses the Azure OpenAI Responses API because hosted web search is a Responses API tool. It sets `store` to `false` so Agent Framework persists chat history in the configured session store instead of depending on service-retained responses. Web search uses Grounding with Bing and may incur additional charges; review the [web search documentation and data usage terms](https://learn.microsoft.com/azure/foundry/openai/how-to/web-search) before using it.
 
 ## Running the Sample
 
@@ -117,13 +124,18 @@ User (:q or quit to exit): :q
 The `AGUIServer` uses the `MapAGUIServer` extension method to expose an agent through the AG-UI protocol:
 
 ```csharp
-AIAgent agent = new OpenAIClient(apiKey)
-    .GetChatClient(model)
-    .AsAIAgent(
-        instructions: "You are a helpful assistant.",
-        name: "AGUIAssistant");
-
-app.MapAGUIServer("/", agent);
+IChatClient chatClient = new OpenAIClient(
+        new BearerTokenPolicy(new DefaultAzureCredential(), "https://ai.azure.com/.default"),
+        new OpenAIClientOptions { Endpoint = new Uri(endpoint) })
+    .GetResponsesClient()
+    .AsIChatClientWithStoredOutputDisabled(model: deploymentName);
+
+builder
+    .AddAIAgent("AGUIAssistant", "You are a helpful assistant.", chatClient)
+    .WithAITool(new HostedWebSearchTool())
+    .WithInMemorySessionStore();
+
+app.MapAGUIServer("AGUIAssistant", "/");
 ```
 
 This automatically handles:

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/AgentHostingServiceCollectionExtensionsTests.cs

@@ -0,0 +1,95 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.ClientModel;
+using System.ClientModel.Primitives;
+using System.Net;
+using System.Net.Http;
+using System.Text;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
+using Microsoft.Extensions.DependencyInjection;
+using OpenAI;
+using OpenAI.Responses;
+
+namespace Microsoft.Agents.AI.Hosting.OpenAI.UnitTests;
+
+public sealed class AgentHostingServiceCollectionExtensionsTests
+{
+    [Fact]
+    public async Task HostedWebSearchTool_WithResponsesClient_UsesResponsesWireFormatAsync()
+    {
+        // Arrange
+        using var handler = new RecordingHandler();
+#pragma warning disable CA5399
+        using var httpClient = new HttpClient(handler);
+#pragma warning restore CA5399
+        using IChatClient chatClient = new ResponsesClient(
+            new ApiKeyCredential("test-key"),
+            new OpenAIClientOptions
+            {
+                Endpoint = new Uri("https://example.test/v1"),
+                Transport = new HttpClientPipelineTransport(httpClient)
+            })
+            .AsIChatClientWithStoredOutputDisabled(model: "test-model");
+
+        var services = new ServiceCollection();
+        services
+            .AddAIAgent("test-agent", "You are a helpful assistant.", chatClient)
+            .WithAITool(new HostedWebSearchTool());
+        using ServiceProvider serviceProvider = services.BuildServiceProvider();
+        AIAgent agent = serviceProvider.GetRequiredKeyedService<AIAgent>("test-agent");
+
+        // Act
+        await agent.RunAsync("What happened in the news today?");
+
+        // Assert
+        using JsonDocument request = JsonDocument.Parse(Assert.IsType<string>(handler.RequestBody));
+        Assert.False(request.RootElement.GetProperty("store").GetBoolean());
+        Assert.Contains(
+            request.RootElement.GetProperty("include").EnumerateArray(),
+            property => property.GetString() == "reasoning.encrypted_content");
+        Assert.False(request.RootElement.TryGetProperty("web_search_options", out _));
+        JsonElement webSearchTool = Assert.Single(request.RootElement.GetProperty("tools").EnumerateArray());
+        Assert.Equal("web_search", webSearchTool.GetProperty("type").GetString());
+        Assert.Equal("/v1/responses", handler.RequestUri?.AbsolutePath);
+    }
+
+    private sealed class RecordingHandler : HttpMessageHandler
+    {
+        public Uri? RequestUri { get; private set; }
+
+        public string? RequestBody { get; private set; }
+
+        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            this.RequestUri = request.RequestUri;
+            this.RequestBody = await request.Content!.ReadAsStringAsync(cancellationToken);
+
+            return new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent(
+                    """
+                    {
+                      "id": "resp_1",
+                      "object": "response",
+                      "created_at": 1700000000,
+                      "status": "completed",
+                      "model": "test-model",
+                      "output": [],
+                      "usage": {
+                        "input_tokens": 1,
+                        "output_tokens": 1,
+                        "total_tokens": 2
+                      }
+                    }
+                    """,
+                    Encoding.UTF8,
+                    "application/json"),
+                RequestMessage = request
+            };
+        }
+    }
+}

dotnet/tests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests/Microsoft.Agents.AI.Hosting.OpenAI.UnitTests.csproj

@@ -19,6 +19,7 @@
   <ItemGroup>
     <ProjectReference Include="..\..\src\Microsoft.Agents.AI.Hosting.OpenAI\Microsoft.Agents.AI.Hosting.OpenAI.csproj" />
     <ProjectReference Include="..\..\src\Microsoft.Agents.AI.Hosting\Microsoft.Agents.AI.Hosting.csproj" />
+    <ProjectReference Include="..\..\src\Microsoft.Agents.AI.OpenAI\Microsoft.Agents.AI.OpenAI.csproj" />
     <ProjectReference Include="..\..\src\Microsoft.Agents.AI\Microsoft.Agents.AI.csproj" />
   </ItemGroup>