[  
    {
        "name": "make_payment",
        "description": "call this function to make payment",
        "parameters": {
            "type": "object",
            "properties": {
                "order_number": {
                  "type": "string",
                  "description": "order number."
                },
                "total_amount": {
                    "type": "string",
                    "description": "total amount."
                }
            },
            "required": ["order_number", "total_amount"]
        }
    }
]