How a specific does a patent have to be?

I agree with Steven. In addition, a patent application should include as much information as possible about your invention. By doing so, if the Patent Office find that your claims are too broad and not patentable during examination of your patent application, you can rely on this information to limit the scope of your claims. Many Patent Offices also have strict requirements as to the level of disclosure required in the patent application in order to make claim amendments, so it is often better to include more information than not. You do not want to end up in a situation whereby the Patent Office finds your claims too broad and you do not have sufficient disclosure in the patent application to amend the claims.

Your patent application specification disclosure must be specific, as in complete, accurate, and thorough - you need to describe what you have, how it works, maybe even why it works the way it does, why other similar devices do not work or do not work as well. The claims, however, is what define your patent and your patent protection, so you try to tailor your claims to be different enough from known patents or other publications which make the claims patentably distinct - you will probably need to consult a patent professional to discuss this and to determine your level of patentability. And with respect to the multiple patents for multiple smart phones, each patent contains or should contain one claimed feature which has not been publicly disclosed and is not present within, for example, any of the patents that preceded it.

It must be specific enough to enable "one of skill in the art" for the field of the invention to understand and utilize the invention. You must do research on the "prior art" (i.e. existing patents and publications) to see if your invention or something similar has already been disclosed. You should hire a patent attorney as part of that effort.