If you're looking to trigger a custom script in your download client to tell Sonarr when to update, you can find more details here:

Overview

Sonarr can execute a custom script when new episodes are imported or a series is renamed, depending on the which action occurred the parameters will be different. Parameters are passed to the script through environment variables (allowing for more flexibility in what we send to the script and not having to worry about a particular order). In all cases the Environment Variables Sonarr sends will be prefixed with Sonarr so, the EventType Sonarr sends would be Sonarr.EventType.

Environment Variables

On Download/On Upgrade
Environment Variable Details
EventType Download
Series.Id Internal ID of the series
Series.Title Title of the series
Series.Path Full path to the series
Series.TvdbId TVDB ID for the series
EpisodeFile.Id Internal ID of the episode file
EpisodeFile.RelativePath Path to the episode file relative to the series' path
EpisodeFile.Path Full path to the episode file
EpisodeFile.SeasonNumber Season number of episode
EpisodeFile.EpisodeNumbers Comma separated list of episode numbers
EpisodeFile.EpisodeAirDates Air date from original network
EpisodeFile.EpisodeAirDatesUtc Air Date with Time in UTC
EpisodeFile.Quality Quality name from Sonarr
EpisodeFile.QualityVersion 1 is the default, 2 for proper, 3+ could be used for anime versions
EpisodeFile.ReleaseGroup Release group, will not be set if it is unknown
EpisodeFile.SceneName Original release name
On Rename
Environment Variable Details
EventType Rename
Series.Id Internal ID of the series
Series.Title Title of the series
Series.Path Full path to the series
Series.TvdbId TVDB ID for the series