websurfer: copy entire message context only when last message is tool…

… message

autogen/agentchat/contrib/web_surfer.py

@@ -344,7 +344,17 @@ def generate_surfer_reply(
 
         # Clone the messages to give context
         self._assistant.chat_messages[self._user_proxy] = list()
-        history = messages[:]
+
+        # If the last message is a tool message it has to be included in context,
+        # otherwise openAI will throw exception that not all tool calls are followed by corresponding tool messages
+        # In a case where the last message is not a tool message, we fallback to default behavior in the library
+        # which is copying all messages except the last one
+        # Issue is described more thoroughly in PR https://github.com/microsoft/autogen/pull/4050
+        if messages[-1].get("role", "assistant") == "tool":
+            history = messages[:]
+        else:
+            history = messages[0 : len(messages) - 1]
+
         for message in history:
             self._assistant.chat_messages[self._user_proxy].append(message)