Cohere (reranking)

Cohere is an AI platform offering reranking models (Cohere Rerank), which are specialized cross-encoders that improve result accuracy after initial retrieval.

In a RAG pipeline, Cohere Rerank operates at the reranking stage: a bi-encoder (embedding) extracts the top 100 candidates, then Cohere Rerank (cross-encoder) selects the top 10 most relevant from that hundred. Cohere Rerank analyzes (query, document) pairs simultaneously, making it significantly more precise than embedding comparison alone, but also slower — which is why it's not suitable for searching millions of documents.

In SEO, Cohere Rerank is useful for building semantic search engines on client sites and in internal linking pipelines (selecting the top 10 best links from 100 nearest neighbors). Alternatives include FlashRank (faster, less precise) and Jina Reranker.

In practice, add reranking to your pipeline only when you have a precision problem with your top 10 results; for small datasets (< 1000 documents), embeddings alone give sufficiently good results.