There are two primary entities when dealing with benefits: Benefit Plans and Benefit Groups.
Benefit Plans define the Type (medical, dental, etc.), Coverage options (employee, employee + spouse, etc.), and Total Monthly Costs (i.e. the premium). Each plan will also show when it went into effect and when it is set to expire. Plans must be configured before you can create Benefit Groups.
Benefit Groups allow you to create a customizable benefit package for specific employee groupings. For example, you may want to have a Benefit Group for all of your full time employees for which you include a Medical, Dental, Vision, and 401K plan. You could then have a separate Benefit Group for your part time employees which allows for Medical only. Plan eligibility rules and group-specific employee pays and company pays amounts are set in benefit groups (with the exception of plans where pays information is set at the employee level).
In addition to getting benefit information through the API, you can also get employee deductions for a given plan and define the dependents associated with your employees. You cannot currently enroll employees or change benefit status through the API.
For GET requests, the owner of the API key used must have access to benefit settings.