harness2
A Python framework that tunes the setup around an AI agent so it does better on unfamiliar professional tasks, for developers running benchmarks.
What it is good for
- Improving an agent's prompts and tools for new tasks
- Comparing agent setups on professional work benchmarks
- Letting an agent refine its approach using its own test runs
At a glance
- Who it is for
- Setup
- Guided command-line setup
Level 4 of 5. You copy and paste commands into a terminal by following the instructions. Comfortable territory for vibe coders.
- Cost
- Free and open source
- Type
- Framework or SDK
- Tasks
- Works with
- OpenCode, Codex, Vertex AI, Gemini 3.5 Flash, GLM-5, Docker
Momentum
- Rank this week
- #9 in builder tools
- Best rank
- #1 week 42, 2026
- Stars gained last week
- +2,195
- GitHub stars
- 21,993
GitHub numbers as of Nov 2, 2026. Updated weekly.
On Hacker News
- Harness2 by Google Research, Recursive Agent Harnessing 81 points, 19 comments, Oct 19, 2026
Ranking history
Official links
Setup steps are on the official pages. We do not repeat them here, since they change.
Questions
- Is harness2 free?
- Yes. It is free and open source (Apache-2.0 license).
- Do I need to know how to code to use harness2?
- You do not need to write code, but setup means copying and pasting commands into a terminal by following its instructions.
- What does harness2 work with?
- According to its own documentation, it works with OpenCode, Codex, Vertex AI, Gemini 3.5 Flash, GLM-5, and Docker.
- What is harness2 good for?
- Improving an agent's prompts and tools for new tasks, comparing agent setups on professional work benchmarks, and letting an agent refine its approach using its own test runs.
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