Just the one if you're using CRA. None if you're embedding react as is.
The answer depends on how you're using react, and what advantages you want to get from it. "How many tools" is not a real question to ask. If you're concerned about ease of development and learning curves, then that gives you an actual goal to optimize for, and it won't coincide with the amount of tools (react is harder to use embedded than with tooling, hence why the latter is more popular).
For each and every tool that is added to my project, it needs to be installed by every developer, it needs to be understood at least on some level by every developer, and it needs to be maintained by someone.
