How Do I Build an Autonomous AI Agent in C# Using Semantic Kernel and .NET 10?

Introduction

AI agents are becoming an important part of modern software development. Instead of just responding to inputs, autonomous AI agents can plan, make decisions, and perform tasks with minimal human intervention.

With .NET 10 and Semantic Kernel, developers can build intelligent AI agents using C#, without needing deep expertise in machine learning. Semantic Kernel acts as a bridge between your application and AI models, helping you orchestrate prompts, memory, and actions.

In this article, we will understand how to build an autonomous AI agent in simple words, step by step, with examples and best practices.

What is an Autonomous AI Agent?

An autonomous AI agent is a system that can:

Understand a goal
Plan steps to achieve it
Execute actions
Learn or improve from context

Example:

"Find trending tech topics and generate a blog post automatically"

The agent will:

Search for topics
Select relevant ones
Generate content

What is Semantic Kernel in .NET?

Semantic Kernel is a framework that helps developers integrate AI capabilities into applications.

It provides:

AI model integration (OpenAI, Azure OpenAI)
Prompt management
Memory handling
Function orchestration

In simple terms, it helps you control how your AI behaves.

Key Components of an AI Agent

Before building, let’s understand the core parts.

1. Kernel (Brain of the Agent)

The Kernel connects your app with AI services.

2. Skills (Functions the Agent Can Perform)

Skills are like abilities of the agent.

Examples:

Summarize text
Generate content
Call APIs

3. Planner (Decision Maker)

The planner decides what steps the agent should take.

4. Memory (Context Storage)

Memory helps the agent remember past interactions.

Step-by-Step: Build an AI Agent in C#

Step 1: Create a .NET 10 Project

dotnet new console -n AIAgentApp
cd AIAgentApp

Step 2: Install Semantic Kernel Package

dotnet add package Microsoft.SemanticKernel

Step 3: Configure AI Model

using Microsoft.SemanticKernel;

var builder = Kernel.CreateBuilder();

builder.AddOpenAIChatCompletion(
    modelId: "gpt-4",
    apiKey: "your-api-key"
);

var kernel = builder.Build();

This connects your app to an AI model.

Step 4: Create a Simple Skill

string prompt = "Write a short blog on {{$topic}}";

var function = kernel.CreateFunctionFromPrompt(prompt);

Step 5: Execute the Skill

var result = await kernel.InvokeAsync(function, new() { ["topic"] = "AI in .NET" });

Console.WriteLine(result);

Now your agent can generate content.

Step 6: Add Memory to the Agent

builder.Services.AddSingleton<IMemoryStore, VolatileMemoryStore>();

Memory helps the agent remember previous tasks.

Step 7: Use a Planner for Autonomy

using Microsoft.SemanticKernel.Planning;

var planner = new SequentialPlanner(kernel);

var plan = await planner.CreatePlanAsync("Write a blog and summarize it");

var output = await kernel.InvokeAsync(plan);

This allows the agent to decide steps automatically.

Step 8: Add External API Integration

You can extend your agent with real-world data.

Example:

public class WeatherSkill
{
    public string GetWeather(string city)
    {
        return $"Weather in {city} is sunny";
    }
}

kernel.ImportPluginFromObject(new WeatherSkill(), "Weather");

Step 9: Combine Everything into an Agent Loop

while (true)
{
    Console.Write("Enter goal: ");
    var goal = Console.ReadLine();

    var plan = await planner.CreatePlanAsync(goal);
    var result = await kernel.InvokeAsync(plan);

    Console.WriteLine(result);
}

Now your agent can continuously accept goals and act on them.

How This Improves Developer Productivity

Reduces manual coding of workflows
Automates repetitive tasks
Speeds up content generation
Enhances application intelligence

Real-World Use Cases

Automated blog generation
Customer support chatbots
Data analysis assistants
Code generation tools

Best Practices for Building AI Agents

1. Keep Prompts Clear

Simple prompts give better results.

2. Limit Token Usage

Helps reduce cost and improve speed.

3. Use Memory Carefully

Store only relevant data.

4. Handle Errors Gracefully

Always validate AI responses.

5. Monitor Performance

Track response time and cost.

Common Mistakes to Avoid

Overloading the agent with too many tasks
Poor prompt design
Ignoring error handling
Not testing with real scenarios

Summary

Building an autonomous AI agent in C# using Semantic Kernel and .NET 10 is a powerful way to create intelligent applications. By combining AI models, skills, planners, and memory, developers can build systems that can think, plan, and act independently. This approach improves productivity, reduces manual work, and opens new possibilities for modern software development in the AI-driven world.