diff --git a/changelog.d/7091.doc b/changelog.d/7091.doc
new file mode 100644
index 0000000000000000000000000000000000000000..463536c8128daabfb1f366b240e466a1da669a43
--- /dev/null
+++ b/changelog.d/7091.doc
@@ -0,0 +1 @@
+Improve the documentation of application service configuration files.
diff --git a/docs/application_services.md b/docs/application_services.md
index 06cb79f1f9ceaed43a53653dab106f9f953e32a7..e4592010a2b5d5125f18c5b21ca8ac54c40a0d2c 100644
--- a/docs/application_services.md
+++ b/docs/application_services.md
@@ -23,9 +23,13 @@ namespaces:
   users:  # List of users we're interested in
     - exclusive: <bool>
       regex: <regex>
+      group_id: <group>
     - ...
   aliases: []  # List of aliases we're interested in
   rooms: [] # List of room ids we're interested in
 ```
 
+`exclusive`: If enabled, only this application service is allowed to register users in its namespace(s).
+`group_id`: All users of this application service are dynamically joined to this group. This is useful for e.g user organisation or flairs.
+
 See the [spec](https://matrix.org/docs/spec/application_service/unstable.html) for further details on how application services work.