Steps to reproduce:

1. Item: Zabbix internal
2. Key: zabbix[proxy,discovery]

Result:

JSON return all info about proxy except Description

{         "name": "proxy1",         "passive": false,         "unencrypted": true,         "psk": false,         "cert": false,         "items": 1173,         "compression": true,         "version": "6.4.1",         "compatibility": 1,         "last_seen": 1,         "hosts": 5,         "requiredperformance": 7.883831     }

Expected:
Proxy Description in JSON response