diff --git a/swh/graph/client.py b/swh/graph/client.py
--- a/swh/graph/client.py
+++ b/swh/graph/client.py
@@ -30,6 +30,35 @@
     def get_lines(self, endpoint, **kwargs):
         yield from self.raw_verb_lines("get", endpoint, **kwargs)
 
+    # Web API endpoints without arguments (bad request)
+
+    def leaves_BR(self):
+        return self.get("leaves")
+
+    def neighbors_BR(self):
+        return self.get("neighbors")
+
+    def visit_nodes_BR(self):
+        return self.get("visit/nodes")
+
+    def visit_edges_BR(self):
+        return self.get("visit/edges")
+
+    def visit_paths_BR(self):
+        return self.get("visit/paths")
+
+    def random_walk_BR(self):
+        return self.get("randomwalk")
+
+    def count_leaves_BR(self):
+        return self.get("leaves/count")
+
+    def count_neighbors_BR(self):
+        return self.get("neighbors/count")
+
+    def count_visit_nodes_BR(self):
+        return self.get("visit/nodes/count")
+
     # Web API endpoints
 
     def stats(self):
diff --git a/swh/graph/server/app.py b/swh/graph/server/app.py
--- a/swh/graph/server/app.py
+++ b/swh/graph/server/app.py
@@ -47,6 +47,10 @@
     )
 
 
+async def argsMissing(request):
+    return aiohttp.web.HTTPBadRequest(text="argument(s) missing")
+
+
 class GraphView(aiohttp.web.View):
     """Base class for views working on the graph, with utility functions"""
 
@@ -297,16 +301,26 @@
             aiohttp.web.get("/", index),
             aiohttp.web.get("/graph", index),
             aiohttp.web.view("/graph/stats", StatsView),
+            aiohttp.web.view("/graph/leaves", argsMissing),
             aiohttp.web.view("/graph/leaves/{src}", LeavesView),
+            aiohttp.web.view("/graph/neighbors", argsMissing),
             aiohttp.web.view("/graph/neighbors/{src}", NeighborsView),
+            aiohttp.web.view("/graph/visit/nodes", argsMissing),
             aiohttp.web.view("/graph/visit/nodes/{src}", VisitNodesView),
+            aiohttp.web.view("/graph/visit/edges", argsMissing),
             aiohttp.web.view("/graph/visit/edges/{src}", VisitEdgesView),
+            aiohttp.web.view("/graph/visit/paths", argsMissing),
             aiohttp.web.view("/graph/visit/paths/{src}", VisitPathsView),
             # temporarily disabled in wait of a proper fix for T1969
             # aiohttp.web.view("/graph/walk/{src}/{dst}", WalkView)
+            aiohttp.web.view("/graph/randomwalk", argsMissing),
+            aiohttp.web.view("/graph/randomwalk/{src}", argsMissing),
             aiohttp.web.view("/graph/randomwalk/{src}/{dst}", RandomWalkView),
+            aiohttp.web.view("/graph/neighbors/count", argsMissing),
             aiohttp.web.view("/graph/neighbors/count/{src}", CountNeighborsView),
+            aiohttp.web.view("/graph/leaves/count", argsMissing),
             aiohttp.web.view("/graph/leaves/count/{src}", CountLeavesView),
+            aiohttp.web.view("/graph/visit/nodes/count", argsMissing),
             aiohttp.web.view("/graph/visit/nodes/count/{src}", CountVisitNodesView),
         ]
     )
diff --git a/swh/graph/tests/test_api_client.py b/swh/graph/tests/test_api_client.py
--- a/swh/graph/tests/test_api_client.py
+++ b/swh/graph/tests/test_api_client.py
@@ -33,6 +33,21 @@
     assert isinstance(stats["outdegree"]["avg"], float)
 
 
+def test_missing_args_endpoints(graph_client):
+    # just a few examples, not exhaustive
+    with raises(RemoteException) as exc_info:
+        list(graph_client.leaves_BR())
+    assert exc_info.value.response.status_code == 400
+
+    with raises(RemoteException) as exc_info:
+        list(graph_client.neighbors_BR())
+    assert exc_info.value.response.status_code == 400
+
+    with raises(RemoteException) as exc_info:
+        list(graph_client.random_walk_BR())
+    assert exc_info.value.response.status_code == 400
+
+
 def test_leaves(graph_client):
     actual = list(
         graph_client.leaves("swh:1:ori:0000000000000000000000000000000000000021")