Update app.py

app.py

@@ -56,61 +56,52 @@ compiled_graph = graph.compile()
 
 # 3) The corrected respond_to_input:
 def respond_to_input(user_input: str) -> str:
-    """
-    We place only a SystemMessage in state["messages"], and pass the actual
-    user_input string as the second argument to invoke().
-    """
-    # (A) First message: describe your tools
+    # 1) The tightened system prompt
     system_msg = SystemMessage(
-    content=(
-        "You are an assistant with access to exactly these tools:\n"
-        "  1) web_search(query:str)\n"
-        "  2) parse_excel(path:str,sheet_name:str)\n"
-        "  3) ocr_image(path:str)\n\n"
-        "⚠️ **IMPORTANT** ⚠️: If (and only if) you need to call one of these tools, "
-        "output exactly one JSON object and nothing else. For example:\n"
-        "```json\n"
-        '{"tool":"web_search","query":"Mercedes Sosa albums 2000-2009"}\n'
-        "```\n"
-        "That JSON must start at the very first character of your response and end at the very last character—"
-        "no quotes, no code fences, no extra explanation. \n\n"
-        "If you do NOT need any tool, simply reply with your final answer as plain text (no JSON)."
-    )
+        content=(
+            "You are an assistant with access to exactly these tools:\n"
+            "  1) web_search(query:str)\n"
+            "  2) parse_excel(path:str,sheet_name:str)\n"
+            "  3) ocr_image(path:str)\n\n"
+            "⚠️ **IMPORTANT** ⚠️: If (and only if) you need to call one of these tools, "
+            "output exactly one JSON object and nothing else. For example:\n"
+            "```json\n"
+            '{"tool":"web_search","query":"Mercedes Sosa albums 2000-2009"}\n'
+            "```\n"
+            "That JSON must start at the very first character of your response and end at the very last character—"
+            "no quotes, no code fences, no extra explanation.\n\n"
+            "If you do NOT need any tool, simply reply with your final answer as plain text (no JSON)."
+        )
     )
 
-    # (B) initial state has only the system prompt
+    # 2) Kick off the graph with only that system prompt
     initial_state = { "messages": [system_msg] }
-
-    # (C) Now invoke, passing user_input separately:
     final_state = compiled_graph.invoke(initial_state, user_input)
 
-    # (D) Pull out the last AIMessage from final_state["messages"]:
+    # 3) Find the last AIMessage the LLM returned
     last_msg = None
-    for msg in final_state["messages"][::-1]:
+    for msg in reversed(final_state["messages"]):
         if isinstance(msg, AIMessage):
             last_msg = msg.content
             break
 
-    # Try to parse it as a tool‐call dict:
+    # 4) Try to parse that as a tool‐call dict
     tool_dict = parse_tool_json(last_msg or "")
     if tool_dict is not None:
-        # run the tool and then feed it back into the LLM:
+        # 4.a) If it’s valid, run the tool
         result = tool_node.run(tool_dict)
-        # Append the tool’s result as an AIMessage, then invoke again:
+        # 4.b) Feed the tool’s output back into the agent a second time
         new_state = {
-            "messages": [
-                *final_state["messages"],
-                AIMessage(content=result)
-            ]
+            "messages": [*final_state["messages"], AIMessage(content=result)]
         }
         second_pass = compiled_graph.invoke(new_state, "")
-        # Get that second pass’s last AIMessage:
-        for msg in second_pass["messages"][::-1]:
+        # 4.c) Return the last AIMessage from that second pass
+        for msg in reversed(second_pass["messages"]):
             if isinstance(msg, AIMessage):
                 return msg.content
         return ""
     else:
-        # No valid tool JSON → treat last_msg as final answer
+        # 5) If it wasn’t valid JSON → just return the plain last_msg
         return last_msg or ""