Guiding inputs

How to help consumers or end user to input relevant data

Request Validation
If this field is set to true, the server must not execute any side effects and only perform implementation-specific validation consistent with the full request.
Request Duplication
some API methods cannot easily be idempotent, such as creating a resource, and there is a need to avoid unnecessary duplication
Grammar Syntax
Output Fields
This means that the server must ignore the presence of output only fields and any indication of it.
... without referring to external documentation, an API user does not know what data to provide to operations that take input.