Well, before everything you need to have a goal, about what will you write? Openings, middle game, end game. Then you'll need all the information you can get, everything available about the initial ideia. You don't need to be a GM or a genius to write a book (Even these GM or whatever studied hard to write theirs books) don't give up, if you want to write, try it.
What are ALL the tools you need to write a chess book?

Do people still read chess books nowadays? I used to enjoy playing through games from ones I had as a kid, but nowadays I just look to videos. Then again I'm not really trying to learn any more either, but even if i was I'm not sure I'd turn to a book.

pencil and paper
He asked for ALL the tools. So he will probably also need a pencil sharpener, some whiteout (or eraser), some glue or something to bind the pages together, and two book covers. Might be easier to just use a three hole punch and a three hole binder.

Here's a humorous take on this interesting subject: https://www.kingpinchess.net/2015/01/how-to-write-a-chess-book-and-make-loads-of-dosh/

The original poster asked a serious question and never got a good answer. Someone or maybe multiple people tried to discourage the poster by stating he needed to be an expert. Shame on you. Why bother to post negative responses. I too am trying to write a tactics book which is different from any that I have seen. My problem is attempting to get the diagrams I need onto the page and formatted properly. I have several writing programs but I do not know if I need specialized software for the task. So, I did a google search on writing chess books - and came across this post.
If anyone actually has any helpful advice then, please, post a reply.
I believe OP was not asking about chess knowledge or skills, but rather writing and publishing tools. Here are two approaches (and there are undoubtedly many more).
1) Cut and paste diagrams into LibreOffice (MS Word). The diagrams could be created in SCID (or any number of applications, like ChessBase, or LucasChess, or online, for example), then a screenshot taken, and then pasted. This leaves the issue of chess notation. And I think that would be simply a matter of typing and formatting the text. This could get a bit frustrating, and I don't have much experience with using these editors, but this is probably the easiest approach for many.
2) Another approach that I think would be preferable is to use LaTeX. Unfortunately, LaTeX has a significant learning curve, but it's not like it's impossible. Ultimately once LaTeX is setup and working, it would be easier, and probably look nicer. You can get started with chess diagrams and chess notation in LaTeX using Overlleaf here: https://www.overleaf.com/learn/latex/Chess_notation For an easy LaTeX installation use MikTeX. https://miktex.org/
When I took up chess again 2 years ago, I bought a few chess books on Amazon. One was so bad I wrote a scathing review about it on Amazon. It was so bad, the author misspelled "pawn" several times. (Called it pond!)
This post originated in 2017 and now I'm wondering if its poster authored that dreadful book. Honestly, it was just ridiculously bad and it was a printed publication, not an e-book!