[plt-scheme] contracts in scribble @defproc: must they actually be in the code, too?

Suppose I'm documenting a function that accepts a procedure that's  
supposed to return a string, but the documented function doesn't  
actually have a contract that checks this.  Should the contract  
specified in the scribble documentation then include the contract (->  
string?) or the contract (-> any) for this argument?

John Clements