At some point during a consultation with each patent client, the potential client asks, “So what information do you need from me?” Not only is this a common question, but also a complex one. The simple answer is taken directly from the rules governing the patent application process- enough for someone in the field to make and use the invention and know exactly what it is you want to protect. Additionally, the application must provide different versions of the invention that the inventor deems covered by the application or wants protection in the application.
However, that answer belies the complexity of patent law, because there is no one way to describe an invention- it depends on the technology and the available information. For devices, the application needs to describe the parts and how those parts work- with one another and to accomplish the end goal of the device. For example, in a bone screw patent application, the way the floating head of the screw connected to the body of the screw, and locked into a set orientation with the body. For pharmaceutical applications, the synthesis of the compound, animal studies, possible prophetic studies, SAR analysis, metabolism, distribution, dosing regimens, and toxicity can all be helpful or critical to the application.
The prior art must also be considered when determining how much information is needed- because the amount of information needed is not determined in a vacuum. Prior art is the information known by the field at the time the invention is made. This includes trade or journal articles (both print and online), web postings, manuscripts, sales documents, and products, though this is not an exhaustive list. The prior art cuts both ways, since the more information known in the field that relates to the invention means the disclosure needs less information, but also increases the requirement to distinguish the invention from what is already known.
Getting back to the initial question- what is needed for a patent application; the answer is as much information as you can provide, but at a minimum enough information for me to figure out your invention.
 For example, the Federal Circuit recently analyzed animal studies and prophetic studies to uphold patent infringement in Novartis Pharma. Corp. v. Accord Healthcare, Inc. No. 2021-1070; p5-7, 10-12 (Fed. Cir. January 3, 2022).