{
  "endpoint": "/api/body-fat-calculator",
  "method": "GET",
  "description": "Calculates the estimated body fat percentage using the US Navy method.",
  "parameters": {
    "gender": { "type": "string", "enum": ["male", "female"], "required": true },
    "heightCm": { "type": "number", "required": true },
    "neckCm": { "type": "number", "required": true },
    "waistCm": { "type": "number", "required": true },
    "hipCm": { "type": "number", "required": false, "description": "Required for female cohort only." }
  },
  "sample_response": {
    "bodyFatPercent": 14.5,
    "category": "Athlete"
  }
}