COBRA-Skills: contextual bandits cut agent skill optimization cost by ~55-58%

GardenDelicious1476 · reddit · 2026-09-13

COBRA-Skills, an open-source research project, frames agent skill optimization as a sequential budget-allocation problem — deciding which skill is worth evaluating next. It keeps a population of candidate skills, estimates utility with a neural predictor, uses LinearUCB to balance exploration/exploitation, evaluates only selected skills on the target agent, and reuses execution feedback for scheduled regeneration, mutation, and crossover. Across 6 agent benchmarks (search QA, spreadsheets, document understanding, math, social reasoning, embodied) and 3 target models: best average performance, 55-58% lower cost than SkillOpt, only 50 optimization examples per benchmark, works under Codex and Claude Code harnesses. Key finding: most savings come from avoiding repeated LLM-based trajectory analysis and skill rewriting, not fewer target-agent executions. Paper: arXiv:2609.11682; code and HF page open.

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