Open Harness

A universal API specification for AI agent harnesses. Build once, run on Claude Code, Goose, LangChain, Letta, and more.

13

Domains

107

Capabilities

5

Harnesses

Documentation

Everything you need to build with Open Harness

API Reference

Complete API specification with all 13 domains, endpoints, types, and examples.

107 Capabilities v0.2.0

Compatibility Matrix

See which capabilities are supported across different harnesses and adapters.

5 Harnesses 4 Adapters

TypeScript SDK

Official client library with full type safety, streaming support, and adapter interface.

@openharness/client Available

Quick Start

// Install the SDK and an adapter
npm install @openharness/client @openharness/adapter-anthropic-agent

// Use it
import { AnthropicAgentAdapter } from "@openharness/adapter-anthropic-agent";

const adapter = new AnthropicAgentAdapter({ apiKey: process.env.ANTHROPIC_API_KEY });

for await (const event of adapter.executeStream({ message: "Hello!" })) {
  if (event.type === "text") process.stdout.write(event.content);
}
      

Adapters

Connect to your favorite AI agent harness

Anthropic Agent SDK

Direct access to Claude with tool use, streaming, and conversations.

💻

Claude Code

Full-featured CLI with skills, MCP, and file operations.

Planned

Goose

Multi-model support with MCP-first architecture.

LangChain Deep Agent

Planning, subagents, and multi-model orchestration.

Letta

Memory-first architecture with full agent lifecycle.