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Prerequisites

Before you begin, make sure you have:
  • .NET 6.0 or later installed
  • An OpenAI API key
  • Visual Studio, VS Code, or your preferred C# IDE

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Installation

Install the AutoGen package, which includes all core features: 
dotnet add package AutoGen
For more granular control, see the Installation Guide.

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Your First Agent Conversation

Let’s create a simple conversation between a user and an AI assistant.
1

Create a new console application

dotnet new console -n AutoGenQuickStart
cd AutoGenQuickStart
dotnet add package AutoGen
2

Set up your OpenAI API key

Set your OpenAI API key as an environment variable:
$env:OPENAI_API_KEY="your-api-key-here"
3

Create the application

Replace the contents of Program.cs with:
Program.cs
using AutoGen;
using AutoGen.OpenAI;

var openAIKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY") 
    ?? throw new Exception("Please set OPENAI_API_KEY environment variable.");

var gpt35Config = new OpenAIConfig(openAIKey, "gpt-3.5-turbo");

// Create an assistant agent
var assistantAgent = new AssistantAgent(
    name: "assistant",
    systemMessage: "You are a helpful assistant that can answer questions and help with tasks.",
    llmConfig: new ConversableAgentConfig
    {
        Temperature = 0,
        ConfigList = [gpt35Config],
    })
    .RegisterPrintMessage(); // Print messages to console

// Create a user proxy agent
var userProxyAgent = new UserProxyAgent(
    name: "user",
    humanInputMode: HumanInputMode.ALWAYS) // Always ask for user input
    .RegisterPrintMessage();

// Start the conversation
await userProxyAgent.InitiateChatAsync(
    receiver: assistantAgent,
    message: "Hey assistant, please help me write a C# function to calculate factorial.",
    maxRound: 10);
4

Run the application

dotnet run
The application will start a conversation where you can interact with the AI assistant. Type your messages and press Enter. The conversation continues until you reach the maximum rounds or terminate it.

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Understanding the Code

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AssistantAgent

The AssistantAgent is an AI-powered agent that uses a language model to generate responses: 
var assistantAgent = new AssistantAgent(
    name: "assistant",
    systemMessage: "You are a helpful assistant.",
    llmConfig: new ConversableAgentConfig
    {
        Temperature = 0,
        ConfigList = [gpt35Config],
    });
  • name: Unique identifier for the agent
  • systemMessage: Instructions that define the agent’s behavior
  • llmConfig: Configuration including model settings and API keys
  • Temperature: Controls randomness (0 = deterministic, 1 = creative)

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UserProxyAgent

The UserProxyAgent represents a human user in the conversation: 
var userProxyAgent = new UserProxyAgent(
    name: "user",
    humanInputMode: HumanInputMode.ALWAYS);
  • HumanInputMode.ALWAYS: Prompts for user input before each message
  • HumanInputMode.NEVER: Fully autonomous (uses default replies)
  • HumanInputMode.TERMINATE: Only prompts when termination is suggested

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Message Printing

The RegisterPrintMessage() middleware nicely formats and prints messages to the console: 
.RegisterPrintMessage()

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InitiateChatAsync

Starts the conversation between agents: 
await userProxyAgent.InitiateChatAsync(
    receiver: assistantAgent,
    message: "Initial message",
    maxRound: 10);

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Autonomous Mode Example

For a fully autonomous conversation without human input: 
using AutoGen;
using AutoGen.OpenAI;

var openAIKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY");
var gpt35Config = new OpenAIConfig(openAIKey, "gpt-3.5-turbo");

var assistant = new AssistantAgent(
    name: "assistant",
    systemMessage: "You are a helpful coding assistant.",
    llmConfig: new ConversableAgentConfig
    {
        Temperature = 0,
        ConfigList = [gpt35Config],
    })
    .RegisterPrintMessage();

var user = new UserProxyAgent(
    name: "user",
    humanInputMode: HumanInputMode.NEVER,
    defaultReply: "Thank you!")
    .RegisterPrintMessage();

await user.InitiateChatAsync(
    receiver: assistant,
    message: "Write a C# function to check if a number is prime.",
    maxRound: 3);

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Next Steps

Agents

Learn more about agent types and configurations

Function Calling

Add custom functions to your agents

Group Chat

Create multi-agent conversations

Code Execution

Execute code snippets dynamically

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Troubleshooting

Make sure you’ve set the OPENAI_API_KEY environment variable correctly. In Windows, you may need to restart your terminal or IDE after setting it.
Ensure you’re using .NET 6.0 or later and that you’ve restored packages:
dotnet restore
Check your internet connection and verify that your OpenAI API key is valid and has sufficient credits.

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