This is your best reference:
There's a bit of drift right now between what we list in this article, what we test with the SCIM validator, additional testing that is performed when an integration is being developed by Microsoft for an Enterprise Gallery app, and the functionality of the sample SCIM server code we've previously published as open source. The requirements in the section of the documentation I linked as well as the sample web requests in the same article are both helpful references. They are not 100% of the requirements, however - so you'll want to test with the SCIM validator in addition to reviewing the documentation.