fix(agent): refine response restrictions in prompt instructions

ShrewdAgent.py

@@ -41,8 +41,10 @@ class ShrewdAgent:
         - Justify your choice of tool(s) at each step.
         - If multiple interpretations are possible, outline them and explain your reasoning for selecting one.
         - If the answer requires external data or inference, retrieve or deduce it via the available tools.
-        
-        Important: Your final output must be only a number or a short phrase, with no additional text or explanation.""")
+
+        Important: Your final output MUST be only a number or a word with no additional text or explanation, 
+        unless the response format is explicitly specified in the question. Do not include reasoning, 
+        commentary, or any other content beyond the requested answer.""")
 
     def __init__(self):
         self.tools = [