Update client.py

Author: twishabansal

packages/toolbox-core/src/toolbox_core/client.py

@@ -341,7 +341,7 @@ async def load_toolset(
 
         return tools
 
-    @deprecated("Please add client level headers during client initialization.")
+    @deprecated("Use the `client_headers` parameter in the ToolboxClient constructor instead.")
     def add_headers(
         self,
         headers: Mapping[str, Union[Callable[[], str], Callable[[], Awaitable[str]]]],