Does that include all forms of stimulation, or do the jailers get to pick which kind? Are all needs rights? If so, is a famine an excuse for a human rights violation (implying that there are circumstantial excuses for violating human rights), or are people living in poor countries forced to be human rights violators?

You can pick anything you want, and say people should have it, but if you want to say there are no excuses for human rights violations then you can't pick anything you want and call it a right.

On the other hand, if you want it to be widely accepted that there are excuses for human rights violations, then it's strongly in your interest to have as many rights as possible. Didn't Saudi Arabia, notorious rights violator, want internet to be declared a right?

My definition of a human right is human rights are inalienable, and they do not require someone else to provide it. The purpose of government is to protect those rights. (As written in the Declaration of Independence.)

The point of jail is to protect society from people who violate other peoples' rights. Jail shouldn't be about punishment, torture, etc.

It's well known that removing stimulation from people causes them to go insane. Hence, such is tantamount from torture. While that isn't specifically about book reading, preventing a person from reading, human contact, etc., is removing stimulation. Removing all stimulation violates human rights.