Recently, Cohere released the latest search model Rerank4, which has a larger context window, helping AI agents find the information they need more efficiently to complete tasks. Compared to the previous Rerank3.5, Rerank4's context window has been expanded to 32K, four times larger.
This enhanced capability allows the model to handle longer documents and evaluate multiple paragraphs simultaneously, capturing relationships that short windows cannot identify. According to Cohere, this expansion significantly improves the ranking accuracy of real document types and enhances the relevance of retrieval results.

Rerank4 comes in two versions: a fast version and a professional version. The fast version is suitable for scenarios requiring speed and accuracy, such as e-commerce, programming, and customer service; the professional version targets tasks requiring deeper reasoning, precision, and analysis, such as risk model generation and data analysis. This year, the importance of enterprise search has continued to rise, especially when AI agents need to obtain more information and context about their organization. Cohere noted that Rerank4 significantly improves the accuracy of enterprise AI search by optimizing initial retrieval results.
Rerank4 uses a cross-encoder architecture, which can process queries and candidates together, capturing subtle semantic relationships and reordering results to highlight the most relevant items. Cohere conducted multiple benchmark tests on Rerank4's performance, and the results showed that it outperformed other competitors in the finance, healthcare, and manufacturing sectors. In addition, Rerank4 continues to support multiple languages, understanding more than 100 languages, and achieving state-of-the-art retrieval capabilities in 10 major commercial languages.
Another highlight of Rerank4 is its self-learning ability, allowing users to customize the model according to common use cases without additional annotated data. Similar to large models like GPT-5.2, users can inform the model about the types of content and document sources they prefer. Cohere also stated that in testing on medical datasets, Rerank4's self-learning ability significantly improved retrieval quality, demonstrating strong competitiveness.
Key points:
🌟 The context window of Rerank4 has been expanded to 32K, significantly improving retrieval accuracy.
🚀 It provides a fast version and a professional version to meet different scenario needs.
📈 The first self-learning re-ranking model, allowing users to customize to enhance model performance.


