diff --git a/lang_agent/graphs/routing.py b/lang_agent/graphs/routing.py
index 93f4e11..e303879 100644
--- a/lang_agent/graphs/routing.py
+++ b/lang_agent/graphs/routing.py
@@ -61,14 +61,12 @@ class RoutingGraph(GraphBase):
         self.workflow = self._build_graph()
     
 
-    def invoke(self, *nargs, as_stream:bool=False, **kwargs):
-        assert len(kwargs) == 0, "due to inp assumptions"
+    def invoke(self, *nargs, as_stream:bool=False, as_raw:bool=False, **kwargs):
+        self._validate_input(*nargs, **kwargs)
 
         if as_stream:
             # TODO： this doesn't stream the entire process, we are blind
             for step in self.workflow.stream({"inp": nargs}, stream_mode="updates", **kwargs):
-                # if "messages" in step:
-                #     step["messages"]["messages"][-1].pretty_print()
                 last_el = jax.tree.leaves(step)[-1]
                 if isinstance(last_el, str):
                     logger.info(last_el)
@@ -78,9 +76,16 @@ class RoutingGraph(GraphBase):
             state = step
         else:
             state = self.workflow.invoke({"inp": nargs})
-            
-        # return state["messages"]
-        return jax.tree.leaves(state)[-1].content
+        
+        msg_list = jax.tree.leaves(state)
+        if as_raw:
+            return msg_list
+
+        return msg_list[-1].content
+    
+    def _validate_input(self, *nargs, **kwargs):
+        assert len(nargs[0]["messages"]) >= 2, "need at least 1 system and 1 human message"
+        assert len(kwargs) == 0, "due to inp assumptions"
     
     def _build_modules(self):
         self.llm = init_chat_model(model=self.config.llm_name,