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Dust agents can automatically reply in selected Slack channels without anyone mentioning the @Dust Slack app. This is useful for dedicated support or Q&A channels where every message should get an agent answer without extra steps. This feature is available in every workspace using the Dust in Slack integration.

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How it works

When auto-reply is enabled for a channel, the agent set as the channel’s default agent responds to messages posted in the channel, not just to @Dust mentions. Two modes are available:
  • All messages: the agent replies to every message in the channel, including replies inside threads.
  • Top-level posts only: the agent replies only to new channel messages, not to replies within threads.
Respond to all messages is unconditional. In this mode, the agent is expected to reply to every message it receives. Agent instructions cannot narrow this behavior by telling the agent to stay silent for messages it considers irrelevant. When the agent produces an empty response, Dust treats it as a failed generation and retries, so instructions such as “reply only when relevant” do not turn this into conditional response behavior. Messages that explicitly mention @Dust follow the standard mention behavior, and messages posted by bots are ignored.

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Set it up

Auto-reply is configured per agent from its Slack channel settings. Only workspace admins can change these settings, and the agent must be published.
  1. In the Agent Builder, open the agent’s Slack Channel Settings.
  2. Select the channel(s) where the agent should reply by default.
  3. Turn on Respond to all messages in channel.
  4. (Optional) Check Top-level posts only to skip replies within threads.
  5. Save.
Private channelsPrivate channels you belong to appear in the channel list after you add the Slack tool to the agent, connect your personal Slack account, and invite @Dust to the channel.

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Troubleshooting

If your agent replies to every message even though its instructions say to answer only when relevant, this is expected when Respond to all messages in channel is enabled. Use mention-only behavior when you need the agent to speak only when it is mentioned. There is no mode that reads every channel message while selectively staying silent based on instructions.