curl --request POST \
  --url https://api.iotools.cloud/v1/tool/rectangle-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "calcMode": "length_width",
  "length": "8",
  "width": "6",
  "unit": "cm",
  "precision": "4"
}
'

{
  "tool": "rectangle-calculator",
  "tool_version": "1.0.2",
  "outputs": {
    "results": [
      {
        "metric": "Length",
        "value": "8 cm"
      },
      {
        "metric": "Width",
        "value": "6 cm"
      },
      {
        "metric": "Area",
        "value": "48 cm²"
      },
      {
        "metric": "Perimeter",
        "value": "28 cm"
      },
      {
        "metric": "Diagonal",
        "value": "10 cm"
      },
      {
        "metric": "Inscribed circle radius",
        "value": "3 cm"
      },
      {
        "metric": "Circumscribed circle radius",
        "value": "5 cm"
      },
      {
        "metric": "Aspect ratio",
        "value": "1.3333:1"
      },
      {
        "metric": "Difference from golden ratio (φ)",
        "value": "17.5955%"
      },
      {
        "metric": "Close to golden ratio?",
        "value": "No"
      }
    ]
  },
  "credits_used": 5,
  "credits_remaining": null
}