It's 2 am here in London, and I'm testing Claude Mythos.

This model is truly mind-blowing, and today is the first time I've "felt the AGI."
Here are my initial Mythos thoughts (the good, the bad, overall summary):
The good:
- Extremely, extremely intelligent coding model. It literally one-shotted entire builds, unlike anything I've seen before. So far, I'm very impressed with Fable's ability to just one-shot entire codebases. You can send prompts and with confidence know Fable can execute.
- Creativity. I haven't seen anyone else mention this. Fable is super creative in design, color palettes, and UI/UX. First time I've ever preferred an Anthropic model over Gemini for design work (not as good as its coding work, but noticeable improvement in design imo).
- Strategy. I'll be using Fable as my "premium" model for all strategic thinking (business, important goals, etc.). This model literally feels like speaking to a genius and has already uncovered things I wouldn't have thought of myself.
- /loops. The most powerful way to use AI right now is Fable + an autonomous workflow (/loop,/goal, etc.). The future of AI is letting these extremely smart models work autonomously for hours on end.
The bad:
- Cost. The most obvious drawback. 2x more expensive than Opus 4.8 means that if you don't have a dedicated AI budget, it's probably not practical to use Fable for anything (you'll just hit limits).
- Availability. Only included in paid plans until June 22; after that, you have to pay for API access. Not really a fan.
- Slow. The model feels as though it's "thinking" through every little decision to return the best possible output. I'd recommend sticking to Opus/Sonnet for quick tasks and only using Fable when absolutely necessary.
- Guardrails. It's annoying to have prompts redirected to Opus - especially on things that aren't dangerous/malicious. A few of my prompts that should've been completed by Fable were redirected. Feels like Anthropic needs to refine this.
Summary:
I'm treating Fable as my "premium" model. It will handle all high-level tasks as I only want the smartest AI working on my most important goals.
If it's within your means, I'd highly recommend setting aside an AI budget so you have access to the best intelligence - this is where the world is headed.
Fable is a huge leap forward for truly autonomous work (just give AI a task and it completes it end-to-end), and while the downsides are annoying, many of them are somewhat expected imo.
Overall, I'm impressed, and this thing feels like a genius in my pocket.