curl --request POST \
  --url https://api.iotools.cloud/v1/tool/curvature-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "functionExpr": "x^2",
  "x": "1"
}
'

{
  "tool": "curvature-calculator",
  "tool_version": "1.0.2",
  "outputs": {
    "curvature": "0.178885",
    "radiusOfCurvature": "5.59017",
    "firstDerivative": "2 * x",
    "secondDerivative": "2",
    "steps": "f(x) = x^2\nf'(x) = 2 * x\nf''(x) = 2\nAt x = 1: f'(x) = 2, f''(x) = 2\nκ = |f''(x)| / (1 + f'(x)²)^(3/2) = |2| / (1 + 2²)^(3/2) = 0.178885\nR = 1 / κ = 1 / 0.178885 = 5.59017"
  },
  "credits_used": 5,
  "credits_remaining": null
}