OpenAI has released a significant update to its Assistants API, enhancing its capabilities to support up to 10,000 files per assistant for knowledge retrieval, which is 500x the previous limit. The update includes new features such as fine-tuned models, streaming, and improved file management with vector store objects for automated file parsing, chunking, and embedding. Additionally, the API now offers better token controls, tool choice, JSON mode support, and vector_store objects, aiming to facilitate developers in building more robust AI assistants.