Google Open-Sources Harness²: Agents Rewrite Their Own Scaffolding, Lifting Benchmarks by Up to 11.8 Points Without Touching Model Weights
Google Cloud AI Research has released Harness², an Apache 2.0 framework that automatically optimizes the "scaffolding" around an AI agent — system prompts, tool guides, memory, sub-agents, skills and more — while leaving model weights untouched. On the LAB legal-agent benchmark it delivered an 11.8 percentage point gain, and a weaker model with an optimized scaffold outperformed a stronger one in its default configuration.