Bridge Evidence: Static Retrieval Utility Does Not Predict Causal Utility in Multi-Step Agentic Search
A new preprint demonstrates that static retrieval utility (SRU)—the standard measure for document usefulness in retrieval systems—is nearly independent of causal utility in multi-step agentic search, with a Spearman correlation of -0.026 across over 23,000 document observations. The study finds that about a third of documents read by an agent are 'bridge documents': they appear irrelevant to static readers but are causally essential, providing discriminative entities that redirect the agent's search. Entities from these bridge documents appear 4.02 times more often in the agent's next query than entities from non-relevant documents.
Why it matters: This work exposes a fundamental limitation in current retrieval evaluation for agentic systems, showing that optimizing for static relevance does not ensure effective multi-step reasoning.
Full story at: arXiv Information Retrieval ↗