New models added to Agent Builder

Agent Builder now offers four additional models when you configure an agent: GLM-5.3, GLM-5.3 Flash, Claude Fable 5.1, and GPT-6 Astra. Pick any of them from the model selector when creating or editing an agent — no setup required.

GLM-5.3 Flash is tuned for faster, lighter-weight tasks, while GLM-5.3, Claude Fable 5.1, and GPT-6 Astra suit more demanding reasoning work. GPT-6 Astra is a higher-cost option, so factor that in when choosing it for high-volume agents.