When the agent opens a subagent it uses the Task tool. The model allow-list still includes many *-fast slugs, and the agent picks them on its own.
I mostly use Grok and Claude. Claude is already expensive; Claude *-fast is much worse. I do not want subagents on any fast variant. I want them to inherit the parent chat model or using the model I specified in prompt really bad, not work, or to have fast / *-fast removed from the Task candidate list.
Is there a setting or other supported way to do that? Right now I cannot stop it, and each subagent spawn can hit a fast model and blow up the bill.
There is no setting today that removes the fast variants from the subagent model list, and I understand the frustration with the cost impact! The intended behavior is that a subagent inherits the parent chat model unless a specific model is chosen, and the agent is instructed to only choose a different model when you explicitly ask for one. We are actively working on giving users firmer control over which models subagents can run.
In the meantime, the most effective workaround is to add a rule along these lines: “When spawning subagents with the Task tool, never pass a model parameter. Subagents must always inherit the parent model unless I explicitly name a model in my prompt.” When the model parameter is left unset, the subagent runs on the parent model.
really bad, not work, or to have