Harness Updating Is Not Harness Benefit: Disentangling Evolution Capabilities in Self-Evolving LLM Agents

In three linesStudy on harness self-evolution (prompts, skills, memories, tools) in LLM agents. Analyzes two capabilities: harness-updating (producing useful updates) and harness-benefit (benefiting from them). Findings: harness-updating is capability-agnostic (Qwen3.5-9B matches Claude Opus gains), while harness-benefit is non-monotonic (mid-tier models benefit most).

Summary generated by Claude — human-verified