microsoft--agent-framework/dotnet/samples/02-agents/AgentWithRAG/AgentWithRAG_Step03_CustomRAGDataSource/Program.cs

// Copyright (c) Microsoft. All rights reserved.

// This sample shows how to use TextSearchProvider to add retrieval augmented generation (RAG)
// capabilities to an AI agent. This shows a mock implementation of a search function,
// which can be replaced with any custom search logic to query any external knowledge base.
// The provider invokes the custom search function
// before each model invocation and injects the results into the model context.

using Azure.AI.Projects;
using Azure.Identity;
using Microsoft.Agents.AI;
using Microsoft.Extensions.AI;

var endpoint = Environment.GetEnvironmentVariable("FOUNDRY_PROJECT_ENDPOINT") ?? throw new InvalidOperationException("FOUNDRY_PROJECT_ENDPOINT is not set.");
var deploymentName = Environment.GetEnvironmentVariable("FOUNDRY_MODEL") ?? "gpt-5.4-mini";

TextSearchProviderOptions textSearchOptions = new()
{
    // Run the search prior to every model invocation and keep a short rolling window of conversation context.
    SearchTime = TextSearchProviderOptions.TextSearchBehavior.BeforeAIInvoke,
    RecentMessageMemoryLimit = 6,
};

// 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.
AIAgent agent = new AIProjectClient(
    new Uri(endpoint),
    new DefaultAzureCredential())
    .AsAIAgent(new ChatClientAgentOptions
    {
        ChatOptions = new() { ModelId = deploymentName, Instructions = "You are a helpful support specialist for Contoso Outdoors. Answer questions using the provided context and cite the source document when available." },
        AIContextProviders = [new TextSearchProvider(MockSearchAsync, textSearchOptions)]
    });

AgentSession session = await agent.CreateSessionAsync();

Console.WriteLine(">> Asking about returns\n");
Console.WriteLine(await agent.RunAsync("Hi! I need help understanding the return policy.", session));

Console.WriteLine("\n>> Asking about shipping\n");
Console.WriteLine(await agent.RunAsync("How long does standard shipping usually take?", session));

Console.WriteLine("\n>> Asking about product care\n");
Console.WriteLine(await agent.RunAsync("What is the best way to maintain the TrailRunner tent fabric?", session));

static Task<IEnumerable<TextSearchProvider.TextSearchResult>> MockSearchAsync(string query, CancellationToken cancellationToken)
{
    // The mock search inspects the user's question and returns pre-defined snippets
    // that resemble documents stored in an external knowledge source.
    List<TextSearchProvider.TextSearchResult> results = [];

    if (query.Contains("return", StringComparison.OrdinalIgnoreCase) || query.Contains("refund", StringComparison.OrdinalIgnoreCase))
    {
        results.Add(new()
        {
            SourceName = "Contoso Outdoors Return Policy",
            SourceLink = "https://contoso.com/policies/returns",
            Text = "Customers may return any item within 30 days of delivery. Items should be unused and include original packaging. Refunds are issued to the original payment method within 5 business days of inspection."
        });
    }

    if (query.Contains("shipping", StringComparison.OrdinalIgnoreCase))
    {
        results.Add(new()
        {
            SourceName = "Contoso Outdoors Shipping Guide",
            SourceLink = "https://contoso.com/help/shipping",
            Text = "Standard shipping is free on orders over $50 and typically arrives in 3-5 business days within the continental United States. Expedited options are available at checkout."
        });
    }

    if (query.Contains("tent", StringComparison.OrdinalIgnoreCase) || query.Contains("fabric", StringComparison.OrdinalIgnoreCase))
    {
        results.Add(new()
        {
            SourceName = "TrailRunner Tent Care Instructions",
            SourceLink = "https://contoso.com/manuals/trailrunner-tent",
            Text = "Clean the tent fabric with lukewarm water and a non-detergent soap. Allow it to air dry completely before storage and avoid prolonged UV exposure to extend the lifespan of the waterproof coating."
        });
    }

    return Task.FromResult<IEnumerable<TextSearchProvider.TextSearchResult>>(results);
}