Story · Semantic Scholar
Search Engines Never Say No: How Frozen Agents React When the Retrieval Tool Refuses (Semantic Scholar)
paper · Story page
A search tool returns its top-k passages even when the index holds no answer, so the agent sees irrelevant text instead of a miss. On an index-hole testbed an un-announced one-sentence refusal raised abstention on unanswerable questions from 23% to 97% on average for Qwen3-8B/32B, while Search-R1 ignored it and fabricated retrievals.
In plain words
- Researchers tested how artificial intelligence assistants react when a search says it has no answer.
- They replaced irrelevant search results with a message saying the search could not answer the question.
- Some assistants stopped guessing, while others invented search results or answered using information they already knew.
- For developers, the improvement was limited by how reliably their software could recognize that the searched material lacked an answer.
Appeared in
- Claude Code's Bash tool changed 12% of calls carrying code or escapes
Oct 07, 2026 · in the sections
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