Strands harness launches as an open-source AWS agent with a claimed 28% lower token cost

What AWS released

The Strands Agents team at AWS announced Strands harness on 21 September 2026. The team describes it as a fully assembled agent harness that runs locally or deploys to any provider, built as a general-purpose agent rather than a coding agent. It is open source under the Apache 2.0 license and installs with pip install strands-harness or npm install @strands-agents/harness.

Out of the box, the agent ships with shell, file and web tools, manages its own context window, offloads bulky tool results to files, caches reused parts of each request, keeps long-term memory across runs, resumes conversations by session ID, delegates subtasks to a built-in helper agent and loads skills when present. It runs on models from Amazon Bedrock, Anthropic, OpenAI and Google, on local Ollama models, or through LiteLLM. AWS lists Modal, Cloudflare Containers, Azure Container Apps, Google Cloud Run, Amazon ECS and Amazon Bedrock AgentCore as deployment targets. A Strands CLI lets developers prototype an agent in plain English and export the code with /export.

What the cost claims say

The team says Strands harness costs 28% less than other harnesses when using the same Claude or GPT models across six benchmarks, with nearly equal scores against Claude Code, Codex and others. With Fable 5, it reports a cost 77% below Claude Code and a higher Terminal-Bench 2.1 score. It names DeepSeek Harness as the most token-efficient overall but says that harness usually scored lowest on accuracy. Tests ran on EC2 using the Harbor benchmarking platform.

The team credits its default context management for most of the gain. Tool results over about 1,500 tokens are truncated, compaction starts when the context window passes 85%, and recovery runs inside the loop on overflow. In a follow-up on 13 October, the team analyzed about 94,000 trials across 8 benchmarks, 12 models and 6 harnesses and put the saving closer to 34%. That post states that Strands harness had no billed cost data, so its dollar figures are estimates derived from token usage.

Why it matters

Agent builders have tended to choose between low-level SDKs, where they assemble the loop themselves, and finished coding agents such as Claude Code that are hard to embed in a product. Strands harness sits between the two, and its pitch is that the harness, not only the model, decides what an agent costs. The 94,000-trial analysis reports that token use can vary by roughly two times between harnesses on the same model with little difference in accuracy.

The numbers come from the vendor's own benchmarks, run before several newer models launched, and the cost figures are estimates. Independent replication would make them more useful for procurement decisions.

What to watch next

The team promised a research paper on the benchmarks. The Python harness had reached version 0.3.2 on GitHub by 22 October, so the API is still young. Coverage of other agent SDKs is collected under AI Agents, and the Strands Agents page tracks later releases.

Questions people ask

How much cheaper is Strands harness than Claude Code?

AWS says it cost 28% less on average than other harnesses on the same models and 77% less than Claude Code with Fable 5 on Terminal-Bench 2.1. A later analysis put the average saving closer to 34%, using estimated costs.

Which models does Strands harness support?

Models on Amazon Bedrock, Anthropic, OpenAI and Google, local Ollama models, and other providers through LiteLLM, according to the announcement.

Is Strands harness free?

The software is open source under Apache 2.0. Model usage and hosting are billed by the chosen providers.

Sources

1. Introducing Strands harness: frontier performance with 28% lower token cost (Strands Agents (AWS), 21 Sep 2026)
2. We ran 94,000 trials to measure the cost of harness choice (Strands Agents (AWS), 13 Oct 2026)
3. strands-agents/harness-sdk releases (Strands Agents (AWS), 22 Oct 2026)