Many developers find that an agent idea works inside Claude Code or Codex, then struggles once they rebuild it with their own loop. The Strands Agents team at AWS is targeting that gap with Strands harness, a fully assembled, general-purpose agent harness. It runs locally or deploys to a cloud provider, ships for Python and TypeScript under Apache 2.0, and starts with one line of code. The team reports 28% lower cost than other harnesses running the same Claude or GPT models across 6 benchmarks, with near-equal accuracy.
Is it deployable? Yes. It runs locally, and a bundled skills file helps your coding agent generate deployment config for AWS, GCP, Azure, Cloudflare, and Modal.
What is Strands Harness
A harness is the system around the model: the loop, tools, context handling, memory, and recovery. Strands already exposed those building blocks through the Strands Harness SDK. Strands harness packages them into working defaults. It is built as a general-purpose agent, not a coding agent.
Out of the box, create_harness() returns an agent that:
Runs on a current reasoning model through Amazon Bedrock, Anthropic, OpenAI, Google, Ollama, or LiteLLM.
Ships shell, file (read, write, edit), and web tools, instead of a bespoke tool per task.
Offloads bulky tool results to files and caches reused parts of each request.
Keeps long-term memory across runs and resumes a conversation from a session ID.
Delegates open-ended subtasks to a built-in helper agent and tracks multi-step work with a checklist.
Loads Agent Skills when it finds them.
Benchmark Setup and the 28% Figure
The Strands Agents team ran distributed benchmarking on Amazon EC2 with Harbor, the evaluation framework from the Terminal-Bench creators. The score is the average across 6 benchmarks: ALFWorld, ContextBench, GAIA, WebShop, τ²-bench, and Terminal-Bench 2.1. Cost is the average dollars per task. Rivals on the chart are Claude Code, Codex, oh-my-pi, OpenCode, and DeepSeek Harness.
One important thing to note. DeepSeek Harness was the most token-efficient harness overall, running about 14% cheaper than Strands harness. It also scored lower on every benchmark. The chart footnote states that including it brought the overall savings figure down to 28%. The highest-scoring point on the chart is Claude Opus 5 on Strands harness, near 85%.
Terminal-Bench 2.1: Same Model, 5 Harnesses
The clearest head-to-head uses Claude Fable 5 on Terminal-Bench 2.1, with 89 trials per harness.
HarnessRun costAccuracyStrands harness$56.2969.7Oh-my-pi$86.8369.7OpenCode$73.4266.3Claude Code$248.0561.8DeepSeek Harness$40.3059.5
Against Claude Code, Strands harness cost 77% less and scored 7.9 points higher. Oh-my-pi matched its 69.7 accuracy at 54% higher cost. DeepSeek Harness was cheaper still, but trailed by 10.2 points. The team also noted that 2 other open-source harnesses performed well on cost and accuracy against Claude Code.