Quick fix

app.py

@@ -2,6 +2,6 @@ from smolagents import launch_gradio_demo
 from typing import Optional
 from tool import UnitConversionTool
 
-tool = TimeZoneConversionTool()
+tool = UnitConversionTool()
 
 launch_gradio_demo(tool)

tool.py

@@ -21,8 +21,8 @@ class UnitConversionTool(Tool):
         }
         conversion = conversions.get((from_unit, to_unit))
         if callable(conversion):
-            return conversion(value)
+            return conversion(float(value))
         elif conversion:
-            return value * conversion
+            return float(value) * conversion
         else:
             return "Conversion not supported."