diff --git a/synapse/replication/http/_base.py b/synapse/replication/http/_base.py
index 4de3825fda..619ddab540 100644
--- a/synapse/replication/http/_base.py
+++ b/synapse/replication/http/_base.py
@@ -151,7 +151,7 @@ class ReplicationEndpoint(object):
                         if e.code != 504 or not cls.RETRY_ON_TIMEOUT:
                             raise
 
-                    logger.warn("send_federation_events_to_master request timed out")
+                    logger.warn("%s request timed out", cls.NAME)
 
                     # If we timed out we probably don't need to worry about backing
                     # off too much, but lets just wait a little anyway.
@@ -190,7 +190,9 @@ class ReplicationEndpoint(object):
         http_server.register_paths(method, [pattern], handler)
 
     def _cached_handler(self, request, txn_id, **kwargs):
-        """Wraps `_handle_request` the responses should be cached.
+        """Called on new incoming requests when caching is enabled. Checks
+        if their is a cached response for the request and returns that,
+        otherwise calls `_handle_request` and caches its response.
         """
         # We just use the txn_id here, but we probably also want to use the
         # other PATH_ARGS as well.
diff --git a/synapse/replication/http/membership.py b/synapse/replication/http/membership.py
index 8ad83e8421..e58bebf12a 100644
--- a/synapse/replication/http/membership.py
+++ b/synapse/replication/http/membership.py
@@ -27,6 +27,16 @@ logger = logging.getLogger(__name__)
 
 class ReplicationRemoteJoinRestServlet(ReplicationEndpoint):
     """Does a remote join for the given user to the given room
+
+    Request format:
+
+        POST /_synapse/replication/remote_join/:room_id/:user_id
+
+        {
+            "requester": ...,
+            "remote_room_hosts": [...],
+            "content": { ... }
+        }
     """
 
     NAME = "remote_join"
@@ -85,6 +95,15 @@ class ReplicationRemoteJoinRestServlet(ReplicationEndpoint):
 
 class ReplicationRemoteRejectInviteRestServlet(ReplicationEndpoint):
     """Rejects the invite for the user and room.
+
+    Request format:
+
+        POST /_synapse/replication/remote_reject_invite/:room_id/:user_id
+
+        {
+            "requester": ...,
+            "remote_room_hosts": [...],
+        }
     """
 
     NAME = "remote_reject_invite"
@@ -153,6 +172,17 @@ class ReplicationRemoteRejectInviteRestServlet(ReplicationEndpoint):
 
 class ReplicationRegister3PIDGuestRestServlet(ReplicationEndpoint):
     """Gets/creates a guest account for given 3PID.
+
+    Request format:
+
+        POST /_synapse/replication/get_or_register_3pid_guest/
+
+        {
+            "requester": ...,
+            "medium": ...,
+            "address": ...,
+            "inviter_user_id": ...
+        }
     """
 
     NAME = "get_or_register_3pid_guest"
@@ -206,6 +236,12 @@ class ReplicationRegister3PIDGuestRestServlet(ReplicationEndpoint):
 
 class ReplicationUserJoinedLeftRoomRestServlet(ReplicationEndpoint):
     """Notifies that a user has joined or left the room
+
+    Request format:
+
+        POST /_synapse/replication/membership_change/:room_id/:user_id/:change
+
+        {}
     """
 
     NAME = "membership_change"