Daily Brief: Fable Launches, but Evals Decide the Route

Fable arrived with the usual launch energy: long-horizon claims, coding examples, and benchmark comparisons. That is useful signal, but it is not enough to justify a product decision. The real test is whether the model improves your own workflows under your constraints.

Product builders need to separate model excitement from product leverage. A model can be impressive and still be the wrong choice for routine work, regulated work, latency-sensitive work, or workflows where review cost eats the gain.

Create a small eval set from real user tasks: one easy routine task, one messy long-context task, one ambiguous planning task, one safety-sensitive task, and one failure case. Compare current model, Fable, and a cheaper fallback using quality, latency, cost, and review burden.

Before adopting any new model, write the routing rule in plain English: "Use this model when..." and "Do not use it when..." If you cannot write that rule, you are not ready to ship it.