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Harness2 (Google Research)

Open-source (Apache 2.0) research framework from Google Cloud AI Research that automatically improves an agent's harness (system prompt, guardrails,…

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What Harness2 (Google Research) does

Open-source (Apache 2.0) research framework from Google Cloud AI Research that automatically improves an agent's harness (system prompt, guardrails, memory, tool guidance, subagents, skills, scripts, plugins) without retraining the model, using a propose-probe-compose loop and keeping lessons for future tasks. Works with OpenCode and Codex executors. Not an officially supported Google product.

Good for

  • Study how to tune an agent's prompts, skills and tools systematically instead of by trial and error
  • Benchmark agent setups on professional tasks before rolling them out

Try this in 10 minutes

  1. Study how to tune an agent's prompts, skills and tools systematically instead of by trial and error. Use the free version: pick one real example from your own business and try just that.
  2. Benchmark agent setups on professional tasks before rolling them out. Put the result next to how you do it today. Is it faster, cheaper or better?
  3. Read the quick-start and note which no-code tools (n8n, Make, Zapier, Claude) it connects to.

Mini-tasks based on common small-business uses for this tool.

Honest take

No red flags in our notes so far

  • Research code: Linux + Python 3.12 + uv.

Pricing

Free, open source (Apache 2.0); you pay for the model calls you run.

Prices as listed by the maker when we last checked (2026-10-19); usually in US dollars. Check the website for current prices.

Latest update

  • 2026-10: open-sourced with paper 'Recursive Agent Harnessing for an Open World' (arXiv 2610.14224).

Is Harness2 (Google Research) worth it? Quick answers

Is Harness2 (Google Research) worth it?

Harness2 (Google Research) is worth a look if it matches a job you already do (Agent infrastructure). It is free or open source, so the main cost is your time to set it up.

How much does Harness2 (Google Research) cost?

Free, open source (Apache 2.0); you pay for the model calls you run.

What is Harness2 (Google Research) used for?

Open-source (Apache 2.0) research framework from Google Cloud AI Research that automatically improves an agent's harness (system prompt, guardrails,… Typical uses: study how to tune an agent's prompts, skills and tools systematically instead of by trial and error; benchmark agent setups on professional tasks before rolling them out.