Authorization notice. harness2 is dual-use. Only use it on software, sites and systems you own or have explicit permission to test.
Who it is forAgent builder who wants to copy the winning edits into a hand-maintained harness instead of re-running refinement
The problemYou get a better score but do not know which of the eight editable components changed or what lesson justified it.
The outcomeA short list of concrete edits (system prompt, guardrails, memory, tool guidance and so on) with their stated evidence, ready to port by hand.
What you need first
- Linux, Python 3.12 and uv for installation
- No credentials needed for the local demo (harness2-demo)
- Model-backed runs need Node.js 20+, the Google Cloud CLI, a Vertex AI project and model IDs in .env, and gcloud application-default login
- LAB needs Pandoc and Poppler; WorkBuddy-Bench needs Docker
- Model-backed benchmark runs incur API costs
Steps
- Finish a refinement run, for example: harness2 --bench lab --k 1 --mode parallel --only-domains antitrust-competition --max-tasks 1
- Open the benchmark folder under runs/ and find the adopted harnesses and reflection notes.
- Compare the adopted harness against the base harness, component by component.
- Note which edits came from the general candidate versus the domain-specific candidate.
- Copy the edits you trust into your own agent setup.
Prompt for your agent
After a google-research/harness2 run on <benchmark>, open the runs/ folder and list every adopted harness edit grouped by component (system prompt, guardrails, memory, tool guidance, subagents, skills, scripts, plugins). Verify each edit has a matching reflection note before recommending I port it.
Caveat. The README does not document the exact file layout inside runs/, so inspect the actual output folders rather than assuming a structure, and treat a single run's lessons as hypotheses.
About harness2
A framework that lets an AI agent keep improving its own setup (prompts, tools, memory, skills) while the model itself stays unchanged. Part of this week's top 10 repos: ranked #2 on Repo Radar. View google-research/harness2 on GitHub.
More with harness2
- Watch an agent improve its own setup in 5 minutes, no API key Run the built-in demo to see both recursion modes edit a harness with real Python executions and zero credentials.
- Boost an office, web or coding agent on WorkBuddy tasks Refine an agent's harness on one WorkBuddy-Bench subset to see if office, web or code results improve.
- Test whether harness edits lift your agent on legal tasks Run one LAB legal-work task with refinement, then judge and report, to see if edits beat the base harness.
- Run a clean benchmark with network limits against rubric leaks Lock down network access before evaluating so an agent cannot look up public benchmark answers.
- Compare parallel and sequential refinement on the same task Run the same benchmark task in both recursion modes to pick the cheaper or stronger refinement strategy.
- Run harness refinement with the Codex executor Switch from the default OpenCode executor to Codex to see how the executor changes refined-harness results.
- Resume a long refinement run after it stops midway Re-issue the same command to continue a multi-task run without redoing finished tasks.
Disclaimer
Deduped lists open-source repositories that belong to other people. We do not own, maintain, audit, or vouch for any of them, and a repo appearing here is not an endorsement or a safety check. The use cases, steps, and prompts are written by AI and may be incomplete, outdated, or just wrong. Where a use case is marked "Seen in the wild", we link to public posts where someone described something similar, but we have not verified those posts and the use case itself is still our AI's own write-up. Use all of this at your own risk. Only run code, commands, or agents on systems and accounts you are authorized to use, and read the code and every command before you run it, especially anything that touches credentials, files, or the network. Nothing here is professional, security, legal, or financial advice. All trademarks and project names belong to their respective owners, and their use here does not imply affiliation. Content is provided as is, without warranties of any kind. Found a mistake, a safety problem, or something you want removed? Email [email protected] and we will look at it promptly. Full disclaimer page