Two new models in one week — how to test them on your own work before you switch

Two of the three AI tools this column has covered since June got new flagship models within two days of each other. Anthropic released Claude Fable 5.1 on 1 September, describing it and its restricted sibling Mythos 5.1 as its “most advanced models for coding and knowledge work.” OpenAI announced GPT-6 Astra on 3 September, calling it “the world’s most intelligent and aligned model,” and it reached Plus subscribers over the following days. Both companies published benchmark scores that mean nothing to anyone running a business, and both new models now appear in the model picker of the app you already use, with conditions attached that I will come to.

If you have spent the past few months building prompts, templates and small routines around one of these tools, this is the week they may have changed underneath you. That is not a reason to panic and it is not a reason to switch. It is a reason to test, and the test is simpler than it sounds.

Benchmarks are not a purchasing decision