AgentRunKit

A lightweight Swift 6 framework for building LLM-powered agents with type-safe tool calling.

Zero dependencies · Full Sendable · Async/await · Cloud + Local · MCP

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Quick Start

import AgentRunKit

let client = OpenAIClient(apiKey: "sk-...", model: "gpt-5.4", baseURL: OpenAIClient.openAIBaseURL)

let weatherTool = try Tool<WeatherParams, String, EmptyContext>(
    name: "get_weather",
    description: "Get the current weather"
) { params, _ in
    "72°F and sunny in \(params.city)"
}

let agent = Agent(client: client, tools: [weatherTool])
let result = try await agent.run(userMessage: "What's the weather in SF?", context: EmptyContext())
if let content = result.content {
    print(content)
}

result.content is optional. Completed runs return finish-tool content, while structural terminal reasons such as max iterations or token budget exhaustion surface through result.finishReason with no final content.

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Documentation

Full documentation including guides and API reference is available on Swift Package Index.

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Installation

Add to your Package.swift:

dependencies: [
    .package(url: "https://github.com/Tom-Ryder/AgentRunKit.git", from: "1.20.1")
]

.target(name: "YourApp", dependencies: ["AgentRunKit"])

For on-device inference, additional targets are available:

• AgentRunKitMLX for MLX on Apple Silicon (requires mlx-swift-lm as a dependency)
• AgentRunKitFoundationModels for Apple Foundation Models (iOS 26+ / macOS 26+, no external dependencies)

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Features

• Agent loop with configurable iteration limits and token budgets
• Streaming with AsyncThrowingStream and @Observable SwiftUI wrapper
• Type-safe tools with compile-time JSON schema validation
• Sub-agent composition with depth control and streaming propagation
• Context management: automatic compaction, pruning, token budgets
• Structured output with JSON schema constraints
• Multimodal input: images, audio, video, PDF
• Text-to-speech with concurrent chunking and MP3 concatenation
• MCP client: stdio transport, tool discovery, JSON-RPC
• Extended thinking / reasoning model support

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Providers

Provider	Description
OpenAIClient	OpenAI and compatible APIs (OpenRouter, Groq, Together, Ollama)
AnthropicClient	Anthropic Messages API
GeminiClient	Google Gemini API
VertexAnthropicClient	Anthropic models on Google Vertex AI
VertexGoogleClient	Google models on Vertex AI
ResponsesAPIClient	OpenAI Responses API with same-substrate continuity replay
FoundationModelsClient	Apple on-device (macOS 26+ / iOS 26+)
MLXClient	On-device via MLX on Apple Silicon

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Requirements

Platform	Version
iOS	18.0+
macOS	15.0+
Swift	6.0+
Xcode	16+

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License

MIT License. See LICENSE for details.