.NET: Add Foundry Toolbox MCP skills discovery sample

dotnet/agent-framework-dotnet.slnx

@@ -174,6 +174,7 @@
     <Project Path="samples/02-agents/AgentsWithFoundry/Agent_Step23_LocalMCP/Agent_Step23_LocalMCP.csproj" />
     <Project Path="samples/02-agents/AgentsWithFoundry/Agent_Step24_CodeInterpreterFileDownload/Agent_Step24_CodeInterpreterFileDownload.csproj" />
     <Project Path="samples/02-agents/AgentsWithFoundry/Agent_Step25_FoundryToolboxMcp/Agent_Step25_FoundryToolboxMcp.csproj" />
+    <Project Path="samples/02-agents/AgentsWithFoundry/Agent_Step26_FoundryToolboxMcpSkills/Agent_Step26_FoundryToolboxMcpSkills.csproj" />
   </Folder>
   <Folder Name="/Samples/02-agents/Evaluation/">
     <Project Path="samples/02-agents/Evaluation/Evaluation_CustomEvals/Evaluation_CustomEvals.csproj" />

dotnet/samples/02-agents/AgentsWithFoundry/Agent_Step26_FoundryToolboxMcpSkills/Agent_Step26_FoundryToolboxMcpSkills.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Azure.AI.Projects" />
+    <PackageReference Include="Azure.Identity" />
+    <PackageReference Include="ModelContextProtocol" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.Foundry\Microsoft.Agents.AI.Foundry.csproj" />
+    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.Mcp\Microsoft.Agents.AI.Mcp.csproj" />
+  </ItemGroup>
+
+</Project>

dotnet/samples/02-agents/AgentsWithFoundry/Agent_Step26_FoundryToolboxMcpSkills/Program.cs

@@ -0,0 +1,93 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// Foundry Toolbox MCP Skills.
+//
+// Uses AgentSkillsProviderBuilder to discover MCP-based skills from a Foundry
+// Toolbox endpoint and inject them as AIContextProviders so the agent can
+// discover and use them at runtime.
+
+using System.Net.Http.Headers;
+using Azure.AI.Projects;
+using Azure.Core;
+using Azure.Identity;
+using Microsoft.Agents.AI;
+using ModelContextProtocol.Client;
+
+// --- Configuration ---
+string endpoint = Environment.GetEnvironmentVariable("AZURE_AI_PROJECT_ENDPOINT")
+    ?? throw new InvalidOperationException("AZURE_AI_PROJECT_ENDPOINT is not set.");
+string deploymentName = Environment.GetEnvironmentVariable("AZURE_AI_MODEL_DEPLOYMENT_NAME") ?? "gpt-5.4-mini";
+string toolboxMcpServerUrl = Environment.GetEnvironmentVariable("FOUNDRY_TOOLBOX_MCP_SERVER_URL")
+    ?? throw new InvalidOperationException("FOUNDRY_TOOLBOX_MCP_SERVER_URL is not set.");
+
+// 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.
+TokenCredential credential = new DefaultAzureCredential();
+
+using var httpClient = new HttpClient(new BearerTokenHandler(credential, "https://ai.azure.com/.default")
+{
+    InnerHandler = new HttpClientHandler(),
+});
+
+// --- Connect to the Foundry Toolbox MCP endpoint ---
+await using McpClient mcpClient = await McpClient.CreateAsync(
+    new HttpClientTransport(
+        new HttpClientTransportOptions
+        {
+            Endpoint = new Uri(toolboxMcpServerUrl),
+            Name = "foundry_toolbox",
+            TransportMode = HttpTransportMode.StreamableHttp,
+            AdditionalHeaders = new Dictionary<string, string>
+            {
+                ["Foundry-Features"] = "Toolboxes=V1Preview",
+            },
+        },
+        httpClient));
+
+// --- Discover MCP-based skills ---
+var skillsProvider = new AgentSkillsProviderBuilder()
+    .UseMcpSkills(mcpClient)
+    .Build();
+
+// --- Create the agent ---
+AIProjectClient aiProjectClient = new(new Uri(endpoint), credential);
+
+AIAgent agent = aiProjectClient.AsAIAgent(
+    options: new ChatClientAgentOptions
+    {
+        Name = "ToolboxMcpSkillsAgent",
+        ChatOptions = new()
+        {
+            ModelId = deploymentName,
+            Instructions = "You are a helpful assistant. Use available skills to answer the user.",
+        },
+        AIContextProviders = [skillsProvider],
+    });
+
+// --- Interactive prompt ---
+Console.Write("User: ");
+string? query = Console.ReadLine();
+
+if (string.IsNullOrWhiteSpace(query))
+{
+    Console.WriteLine("No input provided.");
+    return;
+}
+
+Console.WriteLine($"Assistant: {await agent.RunAsync(query)}");
+
+// ---------------------------------------------------------------------------
+// DelegatingHandler: attaches a fresh Foundry bearer token to every request
+// ---------------------------------------------------------------------------
+internal sealed class BearerTokenHandler(TokenCredential credential, string scope) : DelegatingHandler
+{
+    private readonly TokenRequestContext _tokenContext = new([scope]);
+
+    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+    {
+        AccessToken token = await credential.GetTokenAsync(this._tokenContext, cancellationToken).ConfigureAwait(false);
+        request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token.Token);
+        return await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
+    }
+}

dotnet/samples/02-agents/AgentsWithFoundry/Agent_Step26_FoundryToolboxMcpSkills/README.md

@@ -0,0 +1,32 @@
+# Foundry Toolbox MCP Skills
+
+This sample uses
+`AgentSkillsProviderBuilder` to discover MCP-based skills from a Foundry Toolbox endpoint
+and inject them as `AIContextProviders` so the agent can discover and use them at runtime.
+
+## What this sample demonstrates
+
+- Connecting to a Foundry toolbox's MCP endpoint via Streamable HTTP transport
+- Injecting a fresh Azure AI bearer token (`https://ai.azure.com/.default`) on every MCP request
+- Using `AgentSkillsProviderBuilder.UseMcpSkills(client)` to discover skills from the toolbox
+- Injecting the discovered skills into `AIProjectClient.AsAIAgent(...)` via `AIContextProviders`
+
+## Prerequisites
+
+- A Microsoft Foundry project with a toolbox already configured
+- The toolbox MCP endpoint must expose `skill://index.json` with `skill-md` entries (SEP-2640). If the resource is absent, the sample runs but the skills provider will be empty.
+- Azure CLI installed and authenticated (`az login`)
+
+Set the following environment variables:
+
+```powershell
+$env:AZURE_AI_PROJECT_ENDPOINT="https://your-foundry-service.services.ai.azure.com/api/projects/your-foundry-project"
+$env:AZURE_AI_MODEL_DEPLOYMENT_NAME="gpt-5.4-mini"
+$env:FOUNDRY_TOOLBOX_MCP_SERVER_URL="https://your-foundry-service.services.ai.azure.com/api/projects/your-project/toolboxes/your-toolbox/mcp?api-version=v1"
+```
+
+## Run the sample
+
+```powershell
+dotnet run
+```

dotnet/samples/02-agents/AgentsWithFoundry/README.md

@@ -74,6 +74,7 @@ Some samples require extra tool-specific environment variables. See each sample
 | [Local MCP](./Agent_Step23_LocalMCP/) | Local MCP client with HTTP transport |
 | [Code interpreter file download](./Agent_Step24_CodeInterpreterFileDownload/) | Download container files generated by code interpreter |
 | [Foundry toolbox via MCP](./Agent_Step25_FoundryToolboxMcp/) | Use a Foundry Toolbox from a non-hosted agent via its MCP endpoint |
+| [Foundry toolbox MCP skills](./Agent_Step26_FoundryToolboxMcpSkills/) | Use a Foundry Toolbox with MCP-based skills discovery (SEP-2640) via AIContextProviders |
 
 ## Running the samples