Both "मेरे पास ज़्यादा किताबें हैं।" and "I have more books." are equally "incorrect" without context. They are valid when the speaker intends to say they have more books than the number of books mentioned or encountered previously.
A: These books are all I have.
B: I have more books.
"Too many books" would be "बहुत ज़्यादा किताबें " or "बहुत सारी किताबें".