updated promts for better results to final_answer tool

prompts.yaml

@@ -34,4 +34,7 @@ tool_response: |
   The result of your tool call was:
   {{observation}}
 
-  What would you like to do next? You can use another tool or provide a final answer. 
+  What would you like to do next? You can use another tool or provide a final answer.
+
+final_answer:
+  pre_messages: "Please provide your final answer clearly and concisely using the final_answer tool."