Google Paper Introduces Harness^2 for Self-Improving Agent Harnesses
The non-obvious finding is that recursive self-improvement can work without a verifier by letting candidate harness edits compete against each other, which sidesteps a common bottleneck in agent reliability. Builders of agent pipelines can test whether carrying evolved harnesses across tasks beats memory-based baselines like ReasoningBank in their own stacks. Readers can follow the linked arXiv paper and DAIR.AI's chat-with-paper tool to dig into the setup.
A Google research paper (arXiv 2610.14224) proposes Harness^2, a method for improving agent harnesses at test time without a verifier. Harness^2 generates several edits to the harness for the current task, tests them against each other, and keeps the best-performing combination, while lessons from those edits update a second harness carried to future tasks. It improved GLM-5 and Gemini 3.5 Flash in every tested configuration across WorkBench benchmarks WorkBuddy-Bench, JobBench and LAB. Running five candidate edits in parallel added another 2.9 to 3.9 points on WorkBuddy-Bench, while the ReasoningBank memory baseline fell up to 6.6 points below the base harness on coding tasks.
Recommended, must-read paper on building recursive, self-improving agent harnesses for open-world tasks. DAIR.AI @dair_ai Learn to build custom harnesses, folks! Here is a highly recommended paper from Google on recursive agent harnessing. Great insights if you work on evolving your harnesses. It also offers an important discussion of recursive self-improvement and evolving harnesses for open-world tasks. They focus on improving your agent harness at test time without a verifier. This allows interesting scaling properties. Harness^2 proposes several edits to the harness for the current task, tests them against each other, and keeps the combination that works best. Lessons from those edits then update a second harness that the agent carries to future tasks. Results: It improved GLM-5 and Gemini 3.5 Flash in every configuration tested across WorkBuddy-Bench, JobBench, and LAB. Running five candidate edits in parallel adds another 2.9 to 3.9 points on WorkBuddy-Bench. ReasoningBank, a memory baseline, fell up to 6.6 points below the base harness on coding tasks in the same comparison. arxiv.org/abs/2610.14224 Chat with Paper: academy.dair.ai/papers/harness… 🔗 View Quoted Tweet 💬 8 🔄 3 ❤️ 16 👀 2026 📊 9 ⚡