json_schema: {
    "properties": {
      "length": {
        "description": "The length (for rectangle)",
        "type": "number"
      },
      "radius": {
        "description": "The radius (for circle)",
        "type": "number"
      },
      "shape": {
        "description": "The shape to calculate the area of",
        "enum": [
          "square",
          "rectangle",
          "circle"
        ],
        "type": "string"
      },
      "side": {
        "description": "The side length (for square)",
        "type": "number"
      },
      "width": {
        "description": "The width (for rectangle)",
        "type": "number"
      }
    },
    "required": [
      "shape"
    ],
    "type": "object"
  }