Details on all OO out of the box operations is not something that is documented in one OO document.
For operations related to an OO integration to another application (ie: OO integration to HP Service Manager), there are specific integration guides with more information about the integration. Those can be found on the HP Support Portal, under Downloads > Product Manuals.
For documentation on the OO operations, use the online documentation. From Studio, expanding to a folder or an operation, right-click and choose the option to 'Generate Documentation'. This will bring up the online documentation provided for those operations.