Step02_Plugins.cs

// Copyright (c) Microsoft. All rights reserved.
using System.ComponentModel;
using Microsoft.SemanticKernel;
using Microsoft.SemanticKernel.Agents;
using Microsoft.SemanticKernel.ChatCompletion;
using Microsoft.SemanticKernel.Connectors.OpenAI;

namespace GettingStarted;

/// <summary>
/// Demonstrate creation of <see cref="ChatCompletionAgent"/> with a <see cref="KernelPlugin"/>,
/// and then eliciting its response to explicit user messages.
/// </summary>
public class Step02_Plugins(ITestOutputHelper output) : BaseAgentsTest(output)
{
    private const string HostName = "Host";
    private const string HostInstructions = "Answer questions about the menu.";

    [Fact]
    public async Task UseChatCompletionWithPluginAgentAsync()
    {
        // Define the agent
        ChatCompletionAgent agent =
            new()
            {
                Instructions = HostInstructions,
                Name = HostName,
                Kernel = this.CreateKernelWithChatCompletion(),
                Arguments = new KernelArguments(new OpenAIPromptExecutionSettings() { FunctionChoiceBehavior = FunctionChoiceBehavior.Auto() }),
            };

        // Initialize plugin and add to the agent's Kernel (same as direct Kernel usage).
        KernelPlugin plugin = KernelPluginFactory.CreateFromType<MenuPlugin>();
        agent.Kernel.Plugins.Add(plugin);

        /// Create the chat history to capture the agent interaction.
        ChatHistory chat = [];

        // Respond to user input, invoking functions where appropriate.
        await InvokeAgentAsync("Hello");
        await InvokeAgentAsync("What is the special soup?");
        await InvokeAgentAsync("What is the special drink?");
        await InvokeAgentAsync("Thank you");

        // Local function to invoke agent and display the conversation messages.
        async Task InvokeAgentAsync(string input)
        {
            ChatMessageContent message = new(AuthorRole.User, input);
            chat.Add(message);
            this.WriteAgentChatMessage(message);

            await foreach (ChatMessageContent response in agent.InvokeAsync(chat))
            {
                chat.Add(response);

                this.WriteAgentChatMessage(response);
            }
        }
    }

    private sealed class MenuPlugin
    {
        [KernelFunction, Description("Provides a list of specials from the menu.")]
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1024:Use properties where appropriate", Justification = "Too smart")]
        public string GetSpecials() =>
            """
            Special Soup: Clam Chowder
            Special Salad: Cobb Salad
            Special Drink: Chai Tea
            """;

        [KernelFunction, Description("Provides the price of the requested menu item.")]
        public string GetItemPrice(
            [Description("The name of the menu item.")]
            string menuItem) =>
            "$9.99";
    }
}