Override tool behavior

Hi, I have been using the JSON RAG Search tool but I would like to take more fine grained control over it. What I would like to do ensure it chunks the JSON according to the internal structure of the JSON, only search across specific attributes and return a specific attribute as the source. Is there a point at which I override the tool to extend its behavior or do I need to create my own tool for this purpose?

A second but related question is it possible to reuse the internal vector database or do I need to use an external vector database. Thinking ahead, is there a way to make the existing RAG tools use an external vector database for a production environment?