Search interfaces stop being hand-fixed: SearchWeaver rewrites tools and instructions per corpus, lifting answer accuracy from 71.6% to 78.4%
How well a language-model agent searches depends on the interface it is given, yet existing interfaces are set by hand and applied unchanged to every corpus. SearchWeaver jointly revises corpus artifacts, executable tools and usage instructions using the agent's execution trajectories and task rewards, then selects by downstream search performance. With GPT-5.4-nano, the optimized interfaces raise BrowseComp-Plus answer accuracy from 71.6% to 78.4% and average nDCG@10 across four BRIGHT subsets from 45.7 to 55.0, while cutting tool execution time.