This is a known issue we’re already tracking, and I’ve added your report to it. Right now, the Slack integration can only pick from a fixed list of models, and Fable 5.1 isn’t on that list yet, so it falls back to the closest match (Fable 5).
In the meantime, you can start the agent from the Agents Window in Cursor (or cursor.com/agents) with Fable 5.1 selected in the model picker. For an agent that’s already running from Slack, try switching the model from the model picker at the bottom of the agent view.
We’ll update this thread when Slack can launch Fable 5.1 directly. Sorry for the inconvenience here.
