Reranking
A second pass that re-orders search results after the initial retrieval — to surface the truly most relevant documents at the top. Initial search casts a wide net (fast, approximate). Reranking applies a more accurate but slower model to the top results and puts the best ones first. Adding reranking to a document search system often meaningfully improves the quality of what Claude sees before answering — which means better answers.
In practice
Your search retrieves 20 potentially relevant document chunks. Before sending them all to Claude (expensive and noisy), a reranker scores them by actual relevance to the specific question and you only send the top 5. Reranking is the filter between retrieval and generation — it improves answer quality and cuts cost by removing noise.
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