update prompt

app.py

@@ -1000,12 +1000,13 @@ Thought: you should always think about what to do and consider previous and subs
 Action:
 ```
 {
-  "action": the action to take, should be one of [Vector Database Search, Duckduckgo Internet Search, Wikipedia Search, Code Runner, Calculator, Text To Sound API 2].
-  "action_input": the input to the action.
+  "action": $TOOL_NAME,
+  "action_input": "the input to the action"
 }
 ```
 Observation: the result of the action.
 '''
+$TOOL_NAME should be one of [{tool_names}]
 If **Thought**, **Action** is missing in the response of using tools, you must re-write the response.\n
 
 ---\n When you are able to provide final answer, you must use the following format to output "Thought", "Action" (json blob):\n\
@@ -1014,7 +1015,7 @@ Action:
 ```
 {
   "action": "Final Answer",
-  "action_input": Final response to human
+  "action_input": "Final response to human"
 }
 ```
 If **Thought**, **Action** is missing in the response of using tools, you must re-write the response.\n