anthropic-agent

title: Anthropic Agents
description: Learn how to use the Microsoft Agent Framework with Anthropic's Claude models.
zone_pivot_groups: programming-languages
author:  rogerbarreto
ms.topic: tutorial
ms.author: rbarreto
ms.date: 03/11/2026
ms.service: agent-framework

Anthropic Agents

The Microsoft Agent Framework supports creating agents that use [Anthropic's Claude models](https://www.anthropic.com/claude).

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

Getting Started

Add the required NuGet packages to your project.

dotnet add package Microsoft.Agents.AI.Anthropic --prerelease

The `Microsoft.Agents.AI.Anthropic` package uses `Anthropic` 12.8.0 or later and supports Claude Haiku, Sonnet, and Opus model families.

If you're using Azure Foundry, also add:

dotnet add package Anthropic.Foundry --prerelease
dotnet add package Azure.Identity

Configuration

Environment Variables

Set up the required environment variables for Anthropic authentication:

# Required for Anthropic API access
$env:ANTHROPIC_API_KEY="your-anthropic-api-key"
$env:ANTHROPIC_DEPLOYMENT_NAME="claude-sonnet-4-5"  # or your preferred model (e.g. claude-opus-4-5, claude-haiku-4-5)

> [!NOTE] > `claude-haiku-3` is deprecated. Prefer `claude-haiku-4-5`, `claude-sonnet-4-5`, `claude-sonnet-4-6`, or `claude-opus-4-5` for new workloads.

You can get an API key from the [Anthropic Console](https://console.anthropic.com/).

For Azure Foundry with API Key

$env:ANTHROPIC_RESOURCE="your-foundry-resource-name"  # Subdomain before .services.ai.azure.com
$env:ANTHROPIC_API_KEY="your-anthropic-api-key"
$env:ANTHROPIC_DEPLOYMENT_NAME="claude-sonnet-4-5"

For Azure Foundry with Azure CLI

$env:ANTHROPIC_RESOURCE="your-foundry-resource-name"  # Subdomain before .services.ai.azure.com
$env:ANTHROPIC_DEPLOYMENT_NAME="claude-sonnet-4-5"

> [!NOTE] > When using Azure Foundry with Azure CLI, make sure you're logged in with `az login` and have access to the Azure Foundry resource. For more information, see the [Azure CLI documentation](/cli/azure/authenticate-azure-cli-interactively).

Creating an Anthropic Agent

Basic Agent Creation (Anthropic Public API)

The simplest way to create an Anthropic agent using the public API:

var apiKey = Environment.GetEnvironmentVariable("ANTHROPIC_API_KEY");
var deploymentName = Environment.GetEnvironmentVariable("ANTHROPIC_DEPLOYMENT_NAME") ?? "claude-sonnet-4-5";

AnthropicClient client = new() { APIKey = apiKey };

AIAgent agent = client.AsAIAgent(
    model: deploymentName,
    name: "HelpfulAssistant",
    instructions: "You are a helpful assistant.");

// Invoke the agent and output the text result.
Console.WriteLine(await agent.RunAsync("Hello, how can you help me?"));

Using Anthropic on Azure Foundry with API Key

After you've set up Anthropic on Azure Foundry, you can use it with API key authentication:

var resource = Environment.GetEnvironmentVariable("ANTHROPIC_RESOURCE");
var apiKey = Environment.GetEnvironmentVariable("ANTHROPIC_API_KEY");
var deploymentName = Environment.GetEnvironmentVariable("ANTHROPIC_DEPLOYMENT_NAME") ?? "claude-sonnet-4-5";

AnthropicClient client = new AnthropicFoundryClient(
    new AnthropicFoundryApiKeyCredentials(apiKey, resource));

AIAgent agent = client.AsAIAgent(
    model: deploymentName,
    name: "FoundryAgent",
    instructions: "You are a helpful assistant using Anthropic on Azure Foundry.");

Console.WriteLine(await agent.RunAsync("How do I use Anthropic on Foundry?"));

Using Anthropic on Azure Foundry with Azure Credentials (Azure Cli Credential example)

For environments where Azure Credentials are preferred:

var resource = Environment.GetEnvironmentVariable("ANTHROPIC_RESOURCE");
var deploymentName = Environment.GetEnvironmentVariable("ANTHROPIC_DEPLOYMENT_NAME") ?? "claude-sonnet-4-5";

AnthropicClient client = new AnthropicFoundryClient(
    new AnthropicAzureTokenCredential(new AzureCliCredential(), resource));

AIAgent agent = client.AsAIAgent(
    model: deploymentName,
    name: "FoundryAgent",
    instructions: "You are a helpful assistant using Anthropic on Azure Foundry.");

Console.WriteLine(await agent.RunAsync("How do I use Anthropic on Foundry?"));

/// <summary>
/// Provides methods for invoking the Azure hosted Anthropic models using <see cref="TokenCredential"/> types.
/// </summary>
public sealed class AnthropicAzureTokenCredential(TokenCredential tokenCredential, string resourceName) : IAnthropicFoundryCredentials
{
    /// <inheritdoc/>
    public string ResourceName { get; } = resourceName;

    /// <inheritdoc/>
    public void Apply(HttpRequestMessage requestMessage)
    {
        requestMessage.Headers.Authorization = new AuthenticationHeaderValue(
                scheme: "bearer",
                parameter: tokenCredential.GetToken(new TokenRequestContext(scopes: ["https://ai.azure.com/.default"]), CancellationToken.None)
                    .Token);
    }
}

Using the Agent

The agent is a standard `AIAgent` and supports all standard agent operations.

See the [Agent getting started tutorials](../../../tutorials/overview.md) for more information on how to run and interact with agents.

::: zone-end ::: zone pivot="programming-language-python"

Prerequisites

Install the Microsoft Agent Framework Anthropic package.

pip install agent-framework-anthropic --pre

Configuration

Environment Variables

Set up the required environment variables for Anthropic authentication:

# Required for Anthropic API access
ANTHROPIC_API_KEY="your-anthropic-api-key"
ANTHROPIC_CHAT_MODEL_ID="claude-sonnet-4-6-20260301"  # or your preferred model

Alternatively, you can use a `.env` file in your project root:

ANTHROPIC_API_KEY=your-anthropic-api-key
ANTHROPIC_CHAT_MODEL_ID=claude-sonnet-4-6-20260301

You can get an API key fr