diff --git a/api/client-server/sync.yaml b/api/client-server/sync.yaml
index f1997b61..21af0d1e 100644
--- a/api/client-server/sync.yaml
+++ b/api/client-server/sync.yaml
@@ -77,13 +77,14 @@ paths:
         - in: query
           name: set_presence
           type: string
-          enum: ["offline"]
+          enum: ["offline", "online", "unavailable"]
           description: |-
             Controls whether the client is automatically marked as online by
             polling this API. If this parameter is omitted then the client is
             automatically marked as online when it uses this API. Otherwise if
             the parameter is set to "offline" then the client is not marked as
-            being online when it uses this API.
+            being online when it uses this API. When set to "unavailable", the
+            client is marked as being idle.
           x-example: "offline"
         - in: query
           name: timeout
diff --git a/changelogs/client_server/newsfragments/780.feature b/changelogs/client_server/newsfragments/780.feature
new file mode 100644
index 00000000..74725754
--- /dev/null
+++ b/changelogs/client_server/newsfragments/780.feature
@@ -0,0 +1 @@
+Add more presence options to the ``set_presence`` parameter of ``/sync``. (Thanks @mujx!)