.NET: Support Agent Skills

dotnet/agent-framework-dotnet.slnx

@@ -96,6 +96,10 @@
     <Project Path="samples/GettingStarted/Agents/Agent_Step19_Declarative/Agent_Step19_Declarative.csproj" />
     <Project Path="samples/GettingStarted/Agents/Agent_Step20_AdditionalAIContext/Agent_Step20_AdditionalAIContext.csproj" />
   </Folder>
+  <Folder Name="/Samples/GettingStarted/AgentSkills/">
+    <File Path="samples/GettingStarted/AgentSkills/README.md" />
+    <Project Path="samples/GettingStarted/AgentSkills/Agent_Step01_BasicSkills/Agent_Step01_BasicSkills.csproj" />
+  </Folder>
   <Folder Name="/Samples/GettingStarted/DeclarativeAgents/">
     <Project Path="samples/GettingStarted/DeclarativeAgents/ChatClient/DeclarativeChatClientAgents.csproj" />
   </Folder>

dotnet/samples/GettingStarted/AgentSkills/Agent_Step01_BasicSkills/Agent_Step01_BasicSkills.csproj

@@ -0,0 +1,28 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <NoWarn>$(NoWarn);MAAI001</NoWarn>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Azure.AI.OpenAI" />
+    <PackageReference Include="Azure.Identity" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.OpenAI\Microsoft.Agents.AI.OpenAI.csproj" />
+  </ItemGroup>
+
+  <!-- Copy skills directory to output -->
+  <ItemGroup>
+    <None Include="skills\**\*.*">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>

dotnet/samples/GettingStarted/AgentSkills/Agent_Step01_BasicSkills/Program.cs

@@ -0,0 +1,49 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// This sample demonstrates how to use Agent Skills with a ChatClientAgent.
+// Agent Skills are modular packages of instructions and resources that extend an agent's capabilities.
+// Skills follow the progressive disclosure pattern: advertise -> load -> read resources.
+//
+// This sample includes the expense-report skill:
+//   - Policy-based expense filing with references and assets
+
+using Azure.AI.OpenAI;
+using Azure.Identity;
+using Microsoft.Agents.AI;
+using OpenAI.Responses;
+
+// --- Configuration ---
+string endpoint = Environment.GetEnvironmentVariable("AZURE_OPENAI_ENDPOINT")
+    ?? throw new InvalidOperationException("AZURE_OPENAI_ENDPOINT is not set.");
+string deploymentName = Environment.GetEnvironmentVariable("AZURE_OPENAI_DEPLOYMENT_NAME") ?? "gpt-4o-mini";
+
+// --- Skills Provider ---
+// Discovers skills from the 'skills' directory and makes them available to the agent
+var skillsProvider = new FileAgentSkillsProvider(skillPath: Path.Combine(AppContext.BaseDirectory, "skills"));
+
+// --- Agent Setup ---
+AIAgent agent = new AzureOpenAIClient(new Uri(endpoint), new DefaultAzureCredential())
+    .GetResponsesClient(deploymentName)
+    .AsAIAgent(new ChatClientAgentOptions
+    {
+        Name = "SkillsAgent",
+        ChatOptions = new()
+        {
+            Instructions = "You are a helpful assistant.",
+        },
+        AIContextProviders = [skillsProvider],
+    });
+
+// --- Example 1: Expense policy question (loads FAQ resource) ---
+Console.WriteLine("Example 1: Checking expense policy FAQ");
+Console.WriteLine("---------------------------------------");
+AgentResponse response1 = await agent.RunAsync("Are tips reimbursable? I left a 25% tip on a taxi ride and want to know if that's covered.");
+Console.WriteLine($"Agent: {response1.Text}\n");
+
+// --- Example 2: Filing an expense report (multi-turn with template asset) ---
+Console.WriteLine("Example 2: Filing an expense report");
+Console.WriteLine("---------------------------------------");
+AgentSession session = await agent.CreateSessionAsync();
+AgentResponse response2 = await agent.RunAsync("I had 3 client dinners and a $1,200 flight last week. Return a draft expense report and ask about any missing details.",
+    session);
+Console.WriteLine($"Agent: {response2.Text}\n");

dotnet/samples/GettingStarted/AgentSkills/Agent_Step01_BasicSkills/README.md

@@ -0,0 +1,63 @@
+# Agent Skills Sample
+
+This sample demonstrates how to use **Agent Skills** with a `ChatClientAgent` in the Microsoft Agent Framework.
+
+## What are Agent Skills?
+
+Agent Skills are modular packages of instructions and resources that enable AI agents to perform specialized tasks. They follow the [Agent Skills specification](https://agentskills.io/) and implement the progressive disclosure pattern:
+
+1. **Advertise**: Skills are advertised with name + description (~100 tokens per skill)
+2. **Load**: Full instructions are loaded on-demand via `load_skill` tool
+3. **Resources**: References and other files loaded via `read_skill_resource` tool
+
+## Skills Included
+
+### expense-report
+Policy-based expense filing with spending limits, receipt requirements, and approval workflows.
+- `references/POLICY_FAQ.md` — Detailed expense policy Q&A
+- `assets/expense-report-template.md` — Submission template
+
+## Project Structure
+
+```
+Agent_Step01_BasicSkills/
+├── Program.cs
+├── Agent_Step01_BasicSkills.csproj
+└── skills/
+    └── expense-report/
+        ├── SKILL.md
+        ├── references/
+        │   └── POLICY_FAQ.md
+        └── assets/
+            └── expense-report-template.md
+```
+
+## Running the Sample
+
+### Prerequisites
+- .NET 10.0 SDK
+- Azure OpenAI endpoint with a deployed model
+
+### Setup
+1. Set environment variables:
+   ```bash
+   export AZURE_OPENAI_ENDPOINT="https://your-endpoint.openai.azure.com/"
+   export AZURE_OPENAI_DEPLOYMENT_NAME="gpt-4o-mini"
+   ```
+
+2. Run the sample:
+   ```bash
+   dotnet run
+   ```
+
+### Examples
+
+The sample runs two examples:
+
+1. **Expense policy FAQ** — Asks about tip reimbursement; the agent loads the expense-report skill and reads the FAQ resource
+2. **Filing an expense report** — Multi-turn conversation to draft an expense report using the template asset
+
+## Learn More
+
+- [Agent Skills Specification](https://agentskills.io/)
+- [Microsoft Agent Framework Documentation](../../../../../docs/)

dotnet/samples/GettingStarted/AgentSkills/Agent_Step01_BasicSkills/skills/expense-report/SKILL.md

@@ -0,0 +1,40 @@
+---
+name: expense-report
+description: File and validate employee expense reports according to Contoso company policy. Use when asked about expense submissions, reimbursement rules, receipt requirements, spending limits, or expense categories.
+metadata:
+  author: contoso-finance
+  version: "2.1"
+---
+
+# Expense Report
+
+## Categories and Limits
+
+| Category | Limit | Receipt | Approval |
+|---|---|---|---|
+| Meals — solo | $50/day | >$25 | No |
+| Meals — team/client | $75/person | Always | Manager if >$200 total |
+| Lodging | $250/night | Always | Manager if >3 nights |
+| Ground transport | $100/day | >$15 | No |
+| Airfare | Economy | Always | Manager; VP if >$1,500 |
+| Conference/training | $2,000/event | Always | Manager + L&D |
+| Office supplies | $100 | Yes | No |
+| Software/subscriptions | $50/month | Yes | Manager if >$200/year |
+
+## Filing Process
+
+1. Collect receipts — must show vendor, date, amount, payment method.
+2. Categorize per table above.
+3. Use template: [assets/expense-report-template.md](assets/expense-report-template.md).
+4. For client/team meals: list attendee names and business purpose.
+5. Submit — auto-approved if <$500; manager if $500–$2,000; VP if >$2,000.
+6. Reimbursement: 10 business days via direct deposit.
+
+## Policy Rules
+
+- Submit within 30 days of transaction.
+- Alcohol is never reimbursable.
+- Foreign currency: convert to USD at transaction-date rate; note original currency and amount.
+- Mixed personal/business travel: only business portion reimbursable; provide comparison quotes.
+- Lost receipts (>$25): file Lost Receipt Affidavit from Finance. Max 2 per quarter.
+- For policy questions not covered above, consult the FAQ: [references/POLICY_FAQ.md](references/POLICY_FAQ.md). Answers should be based on what this document and the FAQ state.

dotnet/samples/GettingStarted/AgentSkills/Agent_Step01_BasicSkills/skills/expense-report/assets/expense-report-template.md

@@ -0,0 +1,5 @@
+# Expense Report Template
+
+| Date | Category | Vendor | Description | Amount (USD) | Original Currency | Original Amount | Attendees | Business Purpose | Receipt Attached |
+|------|----------|--------|-------------|--------------|-------------------|-----------------|-----------|------------------|------------------|
+|      |          |        |             |              |                   |                 |           |                  | Yes or No        |

dotnet/samples/GettingStarted/AgentSkills/Agent_Step01_BasicSkills/skills/expense-report/references/POLICY_FAQ.md

@@ -0,0 +1,55 @@
+# Expense Policy — Frequently Asked Questions
+
+## Meals
+
+**Q: Can I expense coffee or snacks during the workday?**
+A: Daily coffee/snacks under $10 are not reimbursable (considered personal). Coffee purchased during a client meeting or team working session is reimbursable as a team meal.
+
+**Q: What if a team dinner exceeds the per-person limit?**
+A: The $75/person limit applies as a guideline. Overages up to 20% are accepted with a written justification (e.g., "client dinner at venue chosen by client"). Overages beyond 20% require pre-approval from your VP.
+
+**Q: Do I need to list every attendee?**
+A: Yes. For client meals, list the client's name and company. For team meals, list all employee names. For groups over 10, you may attach a separate attendee list.
+
+## Travel
+
+**Q: Can I book a premium economy or business class flight?**
+A: Economy class is the standard. Premium economy is allowed for flights over 6 hours. Business class requires VP pre-approval and is generally reserved for flights over 10 hours or medical accommodation.
+
+**Q: What about ride-sharing (Uber/Lyft) vs. rental cars?**
+A: Use ride-sharing for trips under 30 miles round-trip. Rent a car for multi-day travel or when ride-sharing would exceed $100/day. Always choose the compact/standard category unless traveling with 3+ people.
+
+**Q: Are tips reimbursable?**
+A: Tips up to 20% are reimbursable for meals, taxi/ride-share, and hotel housekeeping. Tips above 20% require justification.
+
+## Lodging
+
+**Q: What if the $250/night limit isn't enough for the city I'm visiting?**
+A: For high-cost cities (New York, San Francisco, London, Tokyo, Sydney), the limit is automatically increased to $350/night. No additional approval is needed. For other locations where rates are unusually high (e.g., during a major conference), request a per-trip exception from your manager before booking.
+
+**Q: Can I stay with friends/family instead and get a per-diem?**
+A: No. Contoso reimburses actual lodging costs only, not per-diems.
+
+## Subscriptions and Software
+
+**Q: Can I expense a personal productivity tool?**
+A: Software must be directly related to your job function. Tools like IDE licenses, design software, or project management apps are reimbursable. General productivity apps (note-taking, personal calendar) are not, unless your manager confirms a business need in writing.
+
+**Q: What about annual subscriptions?**
+A: Annual subscriptions over $200 require manager approval before purchase. Submit the approval email with your expense report.
+
+## Receipts and Documentation
+
+**Q: My receipt is faded/damaged. What do I do?**
+A: Try to obtain a duplicate from the vendor. If not possible, submit a Lost Receipt Affidavit (available from the Finance SharePoint site). You're limited to 2 affidavits per quarter.
+
+**Q: Do I need a receipt for parking meters or tolls?**
+A: For amounts under $15, no receipt is required — just note the date, location, and amount. For $15 and above, a receipt or bank/credit card statement excerpt is required.
+
+## Approval and Reimbursement
+
+**Q: My manager is on leave. Who approves my report?**
+A: Expense reports can be approved by your skip-level manager or any manager designated as an alternate approver in the expense system.
+
+**Q: Can I submit expenses from a previous quarter?**
+A: The standard 30-day window applies. Expenses older than 30 days require a written explanation and VP approval. Expenses older than 90 days are not reimbursable except in extraordinary circumstances (extended leave, medical emergency) with CFO approval.

dotnet/samples/GettingStarted/AgentSkills/README.md

@@ -0,0 +1,7 @@
+# AgentSkills Samples
+
+Samples demonstrating Agent Skills capabilities.
+
+| Sample | Description |
+|--------|-------------|
+| [Agent_Step01_BasicSkills](Agent_Step01_BasicSkills/) | Using Agent Skills with a ChatClientAgent, including progressive disclosure and skill resources |

dotnet/samples/GettingStarted/README.md

@@ -18,3 +18,4 @@ of the agent framework.
 |[Agent With Anthropic](./AgentWithAnthropic/README.md)|Getting started with agents using Anthropic Claude|
 |[Workflow](./Workflows/README.md)|Getting started with Workflow|
 |[Model Context Protocol](./ModelContextProtocol/README.md)|Getting started with Model Context Protocol|
+|[Agent Skills](./AgentSkills/README.md)|Getting started with Agent Skills|

dotnet/src/Microsoft.Agents.AI/Microsoft.Agents.AI.csproj

@@ -2,12 +2,14 @@
 
   <PropertyGroup>
     <IsReleaseCandidate>true</IsReleaseCandidate>
-    <NoWarn>$(NoWarn);MEAI001</NoWarn>
+    <NoWarn>$(NoWarn);MEAI001;MAAI001</NoWarn>
   </PropertyGroup>
 
   <PropertyGroup>
     <InjectSharedThrow>true</InjectSharedThrow>
+    <InjectSharedDiagnosticIds>true</InjectSharedDiagnosticIds>
     <InjectDiagnosticClassesOnLegacy>true</InjectDiagnosticClassesOnLegacy>
+    <InjectExperimentalAttributeOnLegacy>true</InjectExperimentalAttributeOnLegacy>
     <InjectTrimAttributesOnLegacy>true</InjectTrimAttributesOnLegacy>
     <InjectIsExternalInitOnLegacy>true</InjectIsExternalInitOnLegacy>
   </PropertyGroup>

dotnet/src/Microsoft.Agents.AI/Skills/FileAgentSkill.cs

@@ -0,0 +1,56 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Represents a loaded Agent Skill discovered from a filesystem directory.
+/// </summary>
+/// <remarks>
+/// Each skill is backed by a <c>SKILL.md</c> file containing YAML frontmatter (name and description)
+/// and a markdown body with instructions. Resource files referenced in the body are validated at
+/// discovery time and read from disk on demand.
+/// </remarks>
+internal sealed class FileAgentSkill
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="FileAgentSkill"/> class.
+    /// </summary>
+    /// <param name="frontmatter">Parsed YAML frontmatter (name and description).</param>
+    /// <param name="body">The SKILL.md content after the closing <c>---</c> delimiter.</param>
+    /// <param name="sourcePath">Absolute path to the directory containing this skill.</param>
+    /// <param name="resourceNames">Relative paths of resource files referenced in the skill body.</param>
+    public FileAgentSkill(
+        SkillFrontmatter frontmatter,
+        string body,
+        string sourcePath,
+        IReadOnlyList<string>? resourceNames = null)
+    {
+        this.Frontmatter = Throw.IfNull(frontmatter);
+        this.Body = Throw.IfNull(body);
+        this.SourcePath = Throw.IfNullOrWhitespace(sourcePath);
+        this.ResourceNames = resourceNames ?? [];
+    }
+
+    /// <summary>
+    /// Gets the parsed YAML frontmatter (name and description).
+    /// </summary>
+    public SkillFrontmatter Frontmatter { get; }
+
+    /// <summary>
+    /// Gets the SKILL.md body content (without the YAML frontmatter).
+    /// </summary>
+    public string Body { get; }
+
+    /// <summary>
+    /// Gets the directory path where the skill was discovered.
+    /// </summary>
+    public string SourcePath { get; }
+
+    /// <summary>
+    /// Gets the relative paths of resource files referenced in the skill body (e.g., "references/FAQ.md").
+    /// </summary>
+    public IReadOnlyList<string> ResourceNames { get; }
+}