How list all possible parameter of a method in CakePHP / detailed Class description?

Hello everyone, maybe my question is trivial but I can not help myself to find answer.

Let say, I want to check all parameters that I can use with a method. Is there any way? For example, I want to setup $validator to check mimeType of the uploaded file.

I checked CakePHP Cookbook but the only thing that I have found is this:

If I read or watch tutorials in the internet, authors of the tutorials use various parameters, and I do not know what is the source of their information (sorry for my English, I hope you understand me). Here is and example:

From where does author of the blog knows that he can set just those parameters? How do I know when I replace ‘image’ with ‘document’ or ‘img’ that this parameter is known for the method and my code will work?

Is there a simple way, how to list all methods within the class and how to list all parameters of these methods easily?

Thank you!