Update app.py

added documentation

app.py

@@ -22,6 +22,16 @@ def my_custom_tool(arg1:str, arg2:int)-> str: #it's import to specify the return
 
 @tool
 def get_calories(meal:str) -> Union[str, None]:
+     """
+    Retrieves the calorie information for a given meal from the OpenFoodFacts API.
+
+    Args:
+        meal (str): The name or description of the meal to search for.
+
+    Returns:
+        Union[str, None]: The calorie information as a string in the format 'X kcal per 100g',
+                          'No data found' if no information is available, or None if the request fails.
+    """
     search_url = f"https://world.openfoodfacts.org/cgi/search.pl"
     params = {
          'search_terms': meal,