Tested on Alpine linux v3.22, OpenRC version 0.62.5.
When starting the command rc-service <service> describe, the following warnings are logged in syslog:
daemon.warn numlock[20440]: ^[[1m^[[36mhealthcheck^[[m: no description
daemon.warn numlock[20441]: ^[[1m^[[36munhealthy^[[m: no description
The example above is from the numlock service, but this occurs on any service.
This warning can be suppressed by adding the description in the service init file or conf file. Or globally in the rc.conf file. I think however, this should not be mandatory, especially for services that don't use the supervise daemon.