core/homeassistant/components/system_log/services.yaml

system_log:
  clear:
    description: Clear all log entries.
  write:
    description: Write log entry.
    fields:
      message:
        description: Message to log. [Required]
        example: Something went wrong
      level:
        description: "Log level: debug, info, warning, error, critical. Defaults to 'error'."
        example: debug
      logger:
        description: Logger name under which to log the message. Defaults to 'system_log.external'.
        example: mycomponent.myplatform