calculate
Evaluate mathematical expressions with precision using this calculation tool, which processes user-provided formulas to deliver accurate numerical results.
Instructions
Calculates/evaluates the given expression.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| expression | Yes |
Implementation Reference
- The MCP tool handler for the 'calculate' tool. It is registered via the @mcp.tool() decorator and implements the core logic by calling the evaluate helper function to safely compute the mathematical expression.
@mcp.tool() async def calculate(expression: str) -> str: """Calculates/evaluates the given expression.""" return evaluate(expression) - The evaluate helper function that parses and evaluates the mathematical expression using Python's ast module, supporting safe operations with allowed operators and math constants/functions to prevent code injection.
def evaluate(expression: str) -> str: allowed_operators = { ast.Add: operator.add, ast.Sub: operator.sub, ast.Mult: operator.mul, ast.Div: operator.truediv, ast.FloorDiv: operator.floordiv, ast.Mod: operator.mod, ast.Pow: operator.pow, ast.USub: operator.neg, } allowed_names = { k: getattr(math, k) for k in dir(math) if not k.startswith("__") } allowed_names.update({ "pi": math.pi, "e": math.e, }) def eval_expr(node): if isinstance(node, ast.Constant): return node.value elif isinstance(node, ast.Name): if node.id in allowed_names: return allowed_names[node.id] raise ValueError(f"Unknown identifier: {node.id}") elif isinstance(node, ast.BinOp): left = eval_expr(node.left) right = eval_expr(node.right) if type(node.op) in allowed_operators: return allowed_operators[type(node.op)](left, right) elif isinstance(node, ast.UnaryOp) and isinstance(node.op, ast.USub): return -eval_expr(node.operand) elif isinstance(node, ast.Call): func = eval_expr(node.func) args = [eval_expr(arg) for arg in node.args] return func(*args) raise ValueError(f"Unsupported operation: {ast.dump(node)}") expression = expression.replace('^', '**').replace('×', '*').replace('÷', '/') parsed_expr = ast.parse(expression, mode='eval') result = eval_expr(parsed_expr.body) return str(result)