strands-agents / harness-sdk

Strands Agents
 A model-driven approach to building AI agents in just a few lines of code.
 Documentation 
 ◆ Samples 
 ◆ MCP Server 
 ◆ Discord 
Strands Agents is an open-source SDK for building and running AI agents in Python and TypeScript. Choose Strands when you would otherwise write your own agent loop: it runs in your process with no hosted control plane, and it covers the jobs a hand-rolled loop grows into. In one SDK you get lifecycle controls (turn limits, token budgets, cancellation, stop reasons), tools and structured output, MCP, multi-agent patterns, memory and sessions, model portability, streaming, guardrails, tracing, and evals.
Using a coding agent? Install the Strands plugin for Claude Code, Codex, or Cursor.
It adds framework selection, scaffolding, tool authoring, MCP server connections, web
framework guides, and LangGraph migration guidance. See
Use Strands with AI coding agents
for install and verification steps.
This monorepo contains Strands harness, the Python and TypeScript SDKs, the documentation site, and supporting packages:
| Directory | Description |
|-----------|-------------|
| `harness-py/` | Python Strands harness: fully assembled agent via `create_harness()` (PyPI · docs) |
| `harness-ts/` | TypeScript Strands harness: fully assembled agent via `createHarness()` (npm · docs) |
| `strands-cli/` | `strands` CLI: prototype and chat with a harness agent from the terminal (npm) |
| `strands-py/` | Python SDK: agent loop, model providers, tools (PyPI · releases) |
| `strands-ts/` | TypeScript SDK: agent loop, model providers, tools (npm · releases) |
| `strands-mcp/` | MCP server that gives coding agents knowledge about building with Strands Agents (PyPI) |
| `site/` | Source for the strandsagents.com documentation site (Astro/Starlight) |
| `team/` | Governance and cross-SDK process docs (tenets, decisions, PR & compatibility guidelines, and `designs/` proposals) |
| `test-infra/` | CDK stack provisioning the AWS resources a subset of integration tests run against (knowledge bases, SSH sandboxes) |
## Why Strands
Build an agent harness. Control it end-to-end.
- **Build your way.** Any model, any cloud. Context management, execution limits, and observability built in before you write a line of config. Swap backends when you scale; your code stays the same.
- **Model agnostic.** First-class support for Amazon Bedrock, Anthropic, OpenAI, and Gemini, plus many more providers and custom ones.
- **Stay in control.** The agent loop traces every decision by default. Hooks let you intercept any step to log it, validate it, or redirect it.
- **Deliver outcomes that work.** Guardrails catch mistakes before they run. Steering handlers let agents correct themselves instead of failing silently.
MCP, streaming, multi-agent patterns, and structured output are all built in.
## Quick Start
The easiest way to get started is with **Strands harness**, a fully assembled, state-of-the-art agent. A single `create_harness()` (Python) or `c