Mythos, Fable 5, Opus: the new AI hierarchy explained
Mythos, Fable 5, Opus, Sonnet, Haiku. If you follow artificial intelligence news, you run into a pile of names without always knowing which is which. Understanding that hierarchy helps you see where the technology is heading, and what it changes for you.
We untangle it all in plain terms, with one thread to follow: the new class of models known as Mythos level, and what it means.
Quick answer: Anthropic offers several AI models ranked by capability. Mythos is the newest and most advanced class, specialized in security and reserved for partners. Fable 5 is the public version of that class, with guardrails. Below it, Opus is the most capable model available to everyone, Sonnet is the balanced one, and Haiku is the fastest. The higher you go, the smarter the AI, but also the more expensive and the more tightly governed.
1. Why are there several models?
Not every need is the same. Answering an email is not the same job as analyzing a hundred-page contract or securing a critical system. So Anthropic offers a range, from the fastest and cheapest to the smartest and most demanding. It is up to you to pick the tool that matches the task.
2. The new Mythos class
Mythos is a jump. It is a class of models that is clearly more powerful, state of the art on expert tasks such as cybersecurity. Its sharpest version is not public, out of caution. Its public, secured version is called Fable 5: it keeps the useful capability and blocks risky uses.
3. The general-purpose range
Below that elite class sit the models most people and companies use day to day.
- Opus: the most capable one available to everyone, ideal for hard, long-running tasks.
- Sonnet: the best balance of speed and intelligence, well suited to production work.
- Haiku: the fastest and the cheapest, cut out for simple tasks.
4. How do you choose for your business?
Good news: you do not need the most powerful model to get value out of it. For most small businesses, a balanced assistant built into your existing tools is plenty. The right reflex is to start from the task, not from the model name.
If you are torn between assistants, our comparison Copilot or ChatGPT for your small business is a good place to start.
5. What the hierarchy teaches us
Raw capability is worth nothing if it is not governed. That is the whole point of the split between Mythos, restricted and cautious, and Fable 5, public and secured. The future of AI is not only more power, it is more power handled well.
Frequently asked questions
What is the difference between Mythos and Fable 5?
Mythos is the most advanced version and it is not public, reserved for partners. Fable 5 is the public version of the same class, with guardrails that block dangerous uses.
Which AI model is the most powerful?
The Mythos class is the most advanced. For everyone else, Fable 5 and then Opus are the most capable, followed by Sonnet and Haiku.
Which model should a small business choose?
Most of the time, a balanced model is enough. Choose based on the task and the tools you already use, not on whichever name sounds most impressive.
Picking the right AI for your business, without guessing
Too many choices, not enough time? We will help you aim straight. Explore our IT services or contact OKTO Solutions in Trois-Rivières.
Sources: Anthropic · Claude model documentation · Fortune · OKTO Solutions
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