diff --git a/changelog.d/4815.misc b/changelog.d/4815.misc
new file mode 100644
index 000000000..b123b36f7
--- /dev/null
+++ b/changelog.d/4815.misc
@@ -0,0 +1 @@
+Add some docstrings.
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 32101eb36..57bb99624 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -1933,15 +1933,34 @@ def _calculate_state(
 
 
 class SyncResultBuilder(object):
-    "Used to help build up a new SyncResult for a user"
+    """Used to help build up a new SyncResult for a user
+
+    Attributes:
+        sync_config (SyncConfig)
+        full_state (bool)
+        since_token (StreamToken)
+        now_token (StreamToken)
+        joined_room_ids (list[str])
+
+        # The following mirror the fields in a sync response
+        presence (list)
+        account_data (list)
+        joined (list[JoinedSyncResult])
+        invited (list[InvitedSyncResult])
+        archived (list[ArchivedSyncResult])
+        device (list)
+        groups (GroupsSyncResult|None)
+        to_device (list)
+    """
     def __init__(self, sync_config, full_state, since_token, now_token,
                  joined_room_ids):
         """
         Args:
-            sync_config(SyncConfig)
-            full_state(bool): The full_state flag as specified by user
-            since_token(StreamToken): The token supplied by user, or None.
-            now_token(StreamToken): The token to sync up to.
+            sync_config (SyncConfig)
+            full_state (bool): The full_state flag as specified by user
+            since_token (StreamToken): The token supplied by user, or None.
+            now_token (StreamToken): The token to sync up to.
+            joined_room_ids (list[str]): List of rooms the user is joined to
         """
         self.sync_config = sync_config
         self.full_state = full_state
@@ -1969,8 +1988,8 @@ class RoomSyncResultBuilder(object):
         Args:
             room_id(str)
             rtype(str): One of `"joined"` or `"archived"`
-            events(list): List of events to include in the room, (more events
-                may be added when generating result).
+            events(list[FrozenEvent]): List of events to include in the room
+                (more events may be added when generating result).
             newly_joined(bool): If the user has newly joined the room
             full_state(bool): Whether the full state should be sent in result
             since_token(StreamToken): Earliest point to return events from, or None
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index d6cfdba51..580fafeb3 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -191,6 +191,25 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
     @defer.inlineCallbacks
     def get_room_events_stream_for_rooms(self, room_ids, from_key, to_key, limit=0,
                                          order='DESC'):
+        """Get new room events in stream ordering since `from_key`.
+
+        Args:
+            room_id (str)
+            from_key (str): Token from which no events are returned before
+            to_key (str): Token from which no events are returned after. (This
+                is typically the current stream token)
+            limit (int): Maximum number of events to return
+            order (str): Either "DESC" or "ASC". Determines which events are
+                returned when the result is limited. If "DESC" then the most
+                recent `limit` events are returned, otherwise returns the
+                oldest `limit` events.
+
+        Returns:
+            Deferred[dict[str,tuple[list[FrozenEvent], str]]]
+                A map from room id to a tuple containing:
+                    - list of recent events in the room
+                    - stream ordering key for the start of the chunk of events returned.
+        """
         from_id = RoomStreamToken.parse_stream_token(from_key).stream
 
         room_ids = yield self._events_stream_cache.get_entities_changed(