"索取资料或合同" can be translated into English as "request for information or contracts".
Here are some alternative expressions with slightly different nuances but similar meanings:
"Inquire about information or contracts" (更侧重于询问、打听)
"Ask for documents or contracts" (如果资料特指文件类，此表达更直接)
"Seek materials or contracts" ("materials" 可以泛指各种资料，但 "information" 更通用)
In most contexts, especially in business or official communications, "request for information or contracts" would be a clear and appropriate choice.