Update calculator.py

calculator.py

@@ -43,7 +43,7 @@ class SimpleCalculatorTool(Tool):
         "This is a tool that returns the result of a simple mathematical expression written in a string."
     )
 
-    inputs = {"expression": {"type": "text", "description": "A simple arithmetical expression, with only +, -, *, /."}
+    inputs = {"expression": {"type": "text", "description": "A simple arithmetical expression, with only +, -, *, /."}}
     output_type = "text"
 
     def forward(self, expression: str):