OpenRouter tests 11 rerankers on a 274-question RAG benchmark
OpenRouter benchmarked 11 rerankers on a 274-question synthetic RAG dataset and found that reranking the top 30 vector-search candidates with voyageai/rerank-3-lite raised precision@1 from 81.0% to 97.1% at about $0.10 per 1,000 queries. The guide recommends retrieving roughly 30 chunks, reranking them, and sending only the top 3 to the LLM, which in its test lifted answer accuracy to 99.3% while cutting answering cost from $0.22 to $0.16 per 1,000 questions. It also flags failure modes: omitting the input_type parameter cost 7 to 12 points of precision@1, and cohere/rerank-v3.5 silently ignores content beyond its 4,096-token limit.