Update app.py

Adding tool decorator

app.py

@@ -156,6 +156,8 @@ def tool_visit_webpage(url:str) -> str:
     vst = VisitWebpageTool()
     ret = vst(url)
     return ret
+
+@tool
 def duckduckgo_search_tool(query:str) -> str:
     '''
     A tool used to initialize the ddg search tool, and to return the top 10 finings