curl --request POST \
  --url https://api.iotools.cloud/v1/tool/stress-strain-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "force": "50000",
  "area": "500",
  "originalLength": "200",
  "elongation": "0.1",
  "material": "structural-steel"
}
'

{
  "tool": "stress-strain-calculator",
  "tool_version": "1.0.2",
  "outputs": {
    "results": [
      {
        "metric": "Stress (σ)",
        "value": "100 MPa"
      },
      {
        "metric": "Strain (ε)",
        "value": "0.0005"
      },
      {
        "metric": "Strain (%)",
        "value": "0.05%"
      },
      {
        "metric": "Elastic modulus (E)",
        "value": "200 GPa"
      }
    ],
    "comparison": "Structural steel (ASTM A36): typical E ≈ 200 GPa — computed value is +0% away."
  },
  "credits_used": 5,
  "credits_remaining": null
}