declarative

Declarative Agents

Declarative agents allow you to define agent configuration using YAML or JSON files instead of writing programmatic code. This approach makes agents easier to define, modify, and share across teams.

:::zone pivot="programming-language-csharp"

Prerequisites

To use declarative agents in C#, add the Microsoft.Agents.AI.Declarative NuGet package to your project, alongside the chat client package for your provider (for example, Azure.AI.OpenAI):

dotnet add package Microsoft.Agents.AI.Declarative --prerelease
dotnet add package Azure.AI.OpenAI
dotnet add package Azure.Identity

The Microsoft.Agents.AI.Declarative package provides the ChatClientPromptAgentFactory type and the CreateFromYamlAsync extension method on PromptAgentFactory used in the examples below.

Define an agent inline with YAML

You can define the full YAML specification as a string directly in your code, then create an AIAgent from it with ChatClientPromptAgentFactory:

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

var endpoint = Environment.GetEnvironmentVariable("AZURE_OPENAI_ENDPOINT")
    ?? throw new InvalidOperationException("AZURE_OPENAI_ENDPOINT is not set.");
var deploymentName = Environment.GetEnvironmentVariable("AZURE_OPENAI_DEPLOYMENT_NAME") ?? "gpt-4o-mini";

// Create the chat client
IChatClient chatClient = new AzureOpenAIClient(
    new Uri(endpoint),
    new DefaultAzureCredential())
        .GetChatClient(deploymentName)
        .AsIChatClient();

// Define the agent using a YAML definition.
var yamlDefinition =
    """
    kind: Prompt
    name: Assistant
    description: Helpful assistant
    instructions: You are a helpful assistant. You answer questions in the language specified by the user. You return your answers in a JSON format.
    model:
        options:
            temperature: 0.9
            topP: 0.95
    outputSchema:
        properties:
            language:
                type: string
                required: true
                description: The language of the answer.
            answer:
                type: string
                required: true
                description: The answer text.
    """;

// Create the agent from the YAML definition.
var agentFactory = new ChatClientPromptAgentFactory(chatClient);
var agent = await agentFactory.CreateFromYamlAsync(yamlDefinition);

// Invoke the agent and output the text result.
Console.WriteLine(await agent!.RunAsync("Tell me a joke about a pirate in English."));

// Invoke the agent with streaming support.
await foreach (var update in agent!.RunStreamingAsync("Tell me a joke about a pirate in French."))
{
    Console.WriteLine(update);
}