https://www.zabbix.com/documentation/current/manual/api/reference/item/create

documentation says, that the use of positional macros ($1,$2… $9 - referring to the first, second… ninth parameter of the item key) is now deprecated.

"params": {
        "name": "Free disk space on $1",
        "key_": "vfs.fs.size[/home/joe/,free]",
        "hostid": "30074", 

API documentation must be changed to not use deprecated item name as an example