Swagger is a third party API framework and not officially tested with the Sitefinity CMS, so at the moment I cannot confirm whether the Swagger API would be compatible with Sitefinity.
The Sitefinity CMS webservice API is made of RESTful webservices, details of the Sitefinity RESTful WCF services can be found here: http://docs.sitefinity.com/for-developers-web-services
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items