Utterly backwards. "We need a login page" is exactly agile; you should be taking more ownership of the product rather than being content to be a dumb code monkey following an explicit spec. Just give me high-level requirements and access to a customer to ask questions.
We used to have waterfall projects where everything is specified upfront and tried to describe a system we don't know about. My point is not to go back to that but just to think deeper about the high level problem to give more directions about a solution the project manager already know about (or can ask the customer during meetings). That just try to prevent useless iterations which doesn't enhancement the solution through a better understanding of the problem but fix communication issue because people with different background don't know how to communicate.