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Getting Started

Prerequisites​

  • .NET 10 SDK
  • AWS credentials configured with Amazon Bedrock access
    • Run aws configure or set AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY environment variables
    • Enable model access in the Bedrock console
Don't have AWS/Bedrock?

You can use any supported model provider. Replace BedrockModel with AnthropicModel, OpenAICompatibleModel, or GeminiModel:

// Anthropic direct API
var model = new AnthropicModel(apiKey: "sk-ant-...", modelId: "claude-sonnet-4-5");

// OpenAI / Azure OpenAI / Ollama
var model = new OpenAICompatibleModel(
    baseUrl: "https://api.openai.com/v1",
    apiKey: "sk-...",
    modelId: "gpt-4o");

// Google Gemini
var model = new GeminiModel(apiKey: "...", modelId: "gemini-2.5-flash");

Install packages​

dotnet add package Jacquard.Core
dotnet add package Jacquard.Models.Bedrock
dotnet add package Jacquard.Tools
dotnet add package Jacquard.SourceGenerator

Your first agent​

Create a new console app and add this code:

using Jacquard.Core;
using Jacquard.Models.Bedrock;
using Jacquard.Tools;
using QuickTools;

var model = new BedrockModel(
    region: "us-east-1",
    modelId: "us.anthropic.claude-haiku-4-5-20251001-v1:0");

// Three tool providers: one built-in, two custom (defined below)
var agent = new Agent(
    model,
    toolProviders: [new CalculatorTool(), new CurrentTimeTool(), new LetterCounterTool()]);

var message = """
    I have 3 requests:
    1. What is the time right now?
    2. Calculate 3111696 / 74088
    3. Tell me how many letter R's are in the word "strawberry" 🍓
    """;

Console.Write("Agent: ");
await foreach (var evt in agent.StreamAsync(message))
{
    if (evt is TextDeltaEvent delta)
        Console.Write(delta.Delta);
}

// ── Custom tools ──────────────────────────────────────────────────────────────
// Decorate a method with [Tool] inside a partial class and the source generator
// emits a fully-typed ITool wrapper with a JSON schema at compile time.
// XML doc comments become the descriptions the model sees when choosing a tool.
// ─────────────────────────────────────────────────────────────────────────────

namespace QuickTools
{
    public sealed partial class LetterCounterTool
    {
        /// <summary>Counts occurrences of a specific letter in a word.</summary>
        /// <param name="word">The input word to search in.</param>
        /// <param name="letter">The single character to count.</param>
        [Tool("Count occurrences of a specific letter in a word.")]
        public int CountLetter(string word, string letter)
        {
            if (letter.Length != 1)
                throw new ArgumentException("Must be a single character.", nameof(letter));
            return word.ToLowerInvariant().Count(c => c == char.ToLowerInvariant(letter[0]));
        }
    }

    public sealed partial class CurrentTimeTool
    {
        /// <summary>Returns the current UTC date and time.</summary>
        [Tool("Returns the current UTC date and time.")]
        public string GetCurrentTime() =>
            DateTimeOffset.UtcNow.ToString("dddd, MMMM d, yyyy HH:mm:ss 'UTC'");
    }
}

Run it:

dotnet run

The agent calls all three tools and streams back a response covering the current time, the calculation result, and the letter count.

What just happened​

  1. CalculatorTool is a built-in tool from Jacquard.Tools
  2. CurrentTimeTool and LetterCounterTool are custom tools — each is a partial class with a [Tool]-decorated method
  3. The Roslyn source generator emitted compile-time ITool wrappers and IToolProvider implementations for all three — no runtime reflection
  4. The agent received the prompt, the model decided which tools to call and in what order, the SDK executed them, and the results were fed back to the model to produce the final streamed response
Custom tool placement

Type declarations must come after top-level statements in the same file. Use a block-body namespace (not file-scoped namespace MyApp;) when mixing with top-level statements. For larger projects, move tool classes to a separate file with a file-scoped namespace.

toolProviders vs tools

Use toolProviders: when passing your [Tool]-decorated classes — the common case. Use tools: when you have pre-built ITool instances, such as from agent.AsTool() or AgentCoreGatewayToolProvider.

Next steps​