Zaiets.ClaudeClient 1.0.0

Zaiets.ClaudeClient

A lightweight, production-ready Claude API client for .NET 8. Supports chat completions, streaming, tool use, and vision — with full DI integration.

Installation

dotnet add package Zaiets.ClaudeClient

Quick Start

using Zaiets.ClaudeClient;

var client = new ClaudeClient(new ClaudeClientOptions
{
    ApiKey = "sk-ant-..."   // or set ANTHROPIC_API_KEY env var
});

var response = await client.CompleteAsync("What is the capital of France?");
Console.WriteLine(response.GetText());
// Output: Paris is the capital of France.

Features

Usage Examples

Multi-turn Conversation

var request = new MessageRequestBuilder()
    .WithModel(ClaudeModels.Sonnet4)
    .WithSystem("You are a helpful assistant.")
    .WithMaxTokens(2048)
    .AddUserMessage("Hello! My name is Alice.")
    .AddAssistantMessage("Hello Alice! How can I help you today?")
    .AddUserMessage("What's my name?")
    .Build();

var response = await client.SendAsync(request);
Console.WriteLine(response.GetText());

Streaming

await foreach (var token in client.StreamTextAsync("Tell me a story about a robot."))
{
    Console.Write(token);
}

Vision

var imageBytes = await File.ReadAllBytesAsync("chart.png");

var request = new MessageRequestBuilder()
    .WithModel(ClaudeModels.Sonnet4)
    .AddUserMessage(Message.UserWithContent(
        new ContentBlockBuilder()
            .AddText("What does this chart show?")
            .AddImageBytes(imageBytes, "image/png")
            .Build()))
    .Build();

var response = await client.SendAsync(request);

Tool Use

var weatherTool = Tool.CreateSimple(
    "get_weather",
    "Returns the current weather for a city",
    ("city", "The city name", true),
    ("unit", "celsius or fahrenheit", false));

var orchestrator = new ToolOrchestrator(client);

var request = new MessageRequestBuilder()
    .WithModel(ClaudeModels.Sonnet4)
    .AddUserMessage("What's the weather in London?")
    .AddTool(weatherTool)
    .Build();

var response = await orchestrator.RunAsync(request,
    async (toolName, input, ct) =>
    {
        if (toolName == "get_weather")
        {
            var city = input.GetProperty("city").GetString();
            return $"It is 18°C and cloudy in {city}.";
        }
        throw new NotSupportedException($"Unknown tool: {toolName}");
    });

Console.WriteLine(response.GetText());

ASP.NET Core / Dependency Injection

// Program.cs
builder.Services.AddClaudeClient(opts =>
{
    opts.ApiKey = builder.Configuration["Anthropic:ApiKey"];
    opts.DefaultModel = ClaudeModels.Sonnet4;
    opts.MaxRetries = 3;
});

// In your controller or service
public class ChatService(ClaudeClient claude)
{
    public async Task<string> AskAsync(string question)
    {
        var response = await claude.CompleteAsync(question);
        return response.GetText();
    }
}

Configuration Reference

Available Models

ClaudeModels.Opus4      // claude-opus-4-5       — Most capable
ClaudeModels.Sonnet4    // claude-sonnet-4-5     — Balanced (default)
ClaudeModels.Haiku4     // claude-haiku-4-5      — Fastest & cheapest
ClaudeModels.Sonnet35   // claude-3-5-sonnet-20241022
ClaudeModels.Haiku35    // claude-3-5-haiku-20241022

Error Handling

using Zaiets.ClaudeClient.Exceptions;

try
{
    var response = await client.CompleteAsync("Hello");
}
catch (ClaudeAuthenticationException)
{
    // Bad or missing API key
}
catch (ClaudeRateLimitException ex)
{
    // 429 — check ex.RetryAfterSeconds
}
catch (ClaudeOverloadedException)
{
    // 529 — Anthropic is overloaded
}
catch (ClaudeApiException ex)
{
    // Other API errors — ex.StatusCode, ex.ErrorType
}

License

MIT — Copyright (c) 2025 Vladyslav Zaiets
https://sarmkadan.com