Best tools for AI assisted technical writing?

I just finished the MVP of a HUGE project (a database) and now I need to write a large amount of technical documentation, I expect around 50 pages. I'm not speaking of API documentation or library documentation, but more of a high level view of the architecture and the algorithms used.

Management tasked me with exploring the opportunity of using AI to help me with this, and to report the outcome. At the moment I'm using IntelliJ WriterSide but the AI auto completion leaves me a bit unhappy: suggestions are both short and not very contextual.

What would you use for this task? I searched a bit, but I didn't find anything that was both relevant to this AND recent