diff --git a/spec.yaml b/spec.yaml
index 069b4c6..c8f86ae 100644
--- a/spec.yaml
+++ b/spec.yaml
@@ -263,34 +263,27 @@ definitions:
             name:
               type: string
               description: |
-                A supported resource type (file, folder, calendar, contact, ...)
+                A supported resource type (file, folder, calendar, contact, ...). At least
+                `file` MUST be supported to be OCM compliant.
               example: file
             shareTypes:
               type: array
-              description: The supported recipient share types
+              description: |
+                The supported recipient share types. At least `user` MUST be supported
+                to be OCM compliant.
               items:
                 type: string
                 enum: ["user", "group", "federation"]
+              example: ["user"]
             protocols:
-              type: object
+              type: array
               description: |
-                The supported protocols to access shares at this endpoint
-              anyOf:
-                - properties:
-                    webdav:
-                      type: string
-                      description: The top-level WebDAV endpoint
-                      example: https://my-cloud-storage.org/ocm
-                - properties:
-                    webapp:
-                      type: string
-                      description: The top-level endpoint for web apps
-                      example: https://my-cloud-storage.org
-                - properties:
-                    datatx:
-                      type: string
-                      description: The top-level endpoint for data transfers
-                      example: https://my-cloud-storage.org
+                The supported protocols to access shares at this endpoint. At least `webdav`
+                MUST be supported to be OCM compliant.
+              items:
+                type: string
+                enum: ["webdav", "webapp", "datatx"]
+              example: ["webdav"]
   NewShare:
     type: object
     required: