Fable 5: 4 prompts to squeeze the most out of the world's most powerful AI

Stripe — the online payments company — handed an AI a task its own engineering team would have spent two months on. The model finished it in a single day.

That's not a keynote slide about five years from now. It happened, and the model is called Fable 5 — the newest and, according to its maker (Anthropic, the company behind Claude), the most powerful publicly available AI model in the world.

And it gets better: until July 19, you get it for free inside your existing subscription. After that it disappears behind an expensive paywall. Most people will waste that week asking it about the weather and summarizing emails. This article is about not wasting it — about four questions that keep paying off long after the window closes.

What's actually happening with Fable 5

Fable 5 is the strongest model Anthropic has released publicly — described as the most capable in their lineup. What does that mean in practice? Beyond the Stripe migration, it was the first model in history to break 90% on core analytics benchmarks (a ten-point jump over the previous version). It holds its attention across millions of words at once, so it can analyze a company's entire archive in a single conversation without losing the thread. There's even a twin version with no safety guardrails — Mythos 5 — available only to a handful of approved customers. The public Fable 5 is the same model, just with the brakes on.

The catch is that it's so in-demand the company can't keep up with the compute. That's why access keeps getting switched on and off, and why it now runs on a "window":

• Until July 19, Fable 5 is available inside the regular subscription (Claude Pro, Max, Team) at no extra cost.
• You can use it for up to 50% of your weekly limit. The rest stays for other models.
• From July 20, every Fable 5 request runs on a separate pool of paid credits, billed by usage — far more expensive. Anthropic says it wants to bring the model back to plans "once capacity allows."

In other words: for the next few days, the smartest publicly available model costs you nothing beyond what you already pay. In a few days, the same thing will cost a fortune. That's the whole "window" — and it's why it's worth knowing what to ask before it closes.

Rule number one: don't waste genius on trivia

There's a temptation to treat a stronger model like a stronger toy — ask it to summarize an email, draft a post, translate some text. That works, but it's a waste. A regular model you have access to all the time handles those just fine.

Here's a better way to think about it: imagine the best engineers in the galaxy land on Earth for one week. You don't ask them to pick your phone wallpaper. You ask them to improve the roads, the universities, and the way we teach — because those things stay with us for years after they leave.

Same with Fable 5. Don't point it at a single task. Point it at your foundations — the things that keep paying off long after the window shuts. In practice, that comes down to four questions.

Prompt #1: Improve the system, not the task

The biggest leverage isn't improving one thing — it's improving the thing that governs all the other things. If you use AI for many tasks, there's a layer underneath: the prompts you reuse, the tools you combine, the repeating patterns. That's your deepest layer. Fix it, and everything above it improves.

The prompt:

"Analyze my entire way of working with AI — the prompts I reuse, the tools I combine, and my repetitive tasks. Find the one layer whose improvement would most upgrade everything else. Rebuild it and show me concretely what to change and how."

Why it works: a regular model improves the task you hand it. A very strong model can look one level up and tell you the problem isn't that one piece of text — it's how you approach ten similar ones. That's a fix that pays off every week.

Prompt #2: A security audit of everything you have online

This one sounds less exciting than the rest, but it's one of the best uses of temporary access to a very smart model. If you've built or commissioned websites, a store, automations, forms, or integrations over the past months, there's almost certainly a hole you don't know about — open access, misconfigured permissions, an unprotected form.

This is your one chance to have everything you own reviewed by the smartest model that's been available — before someone with worse intentions does it.

The prompt:

"Review everything I have online — websites, my store, automations, integrations, and forms. List the security holes and weak points, order them from most to least dangerous, and next to each one explain in plain language how to fix it."

Why it works: security is an area where the gap between a good and a mediocre model is huge. One misses the problem, the other catches it. Since you have the better one for a moment — use it for exactly this.

Prompt #3: Tell me what's about to vanish and what's about to 10x

This is probably the most valuable prompt of the four — especially if you carry that quiet pressure of "everyone's talking about AI, I'm doing a dozen things at once, and I don't know if I'm heading the right way." Instead of reading ten more trend articles, ask directly.

The prompt:

"Look at everything I do in my business and work. Tell me which of my activities artificial intelligence will soon take over and make worthless, and which ones it could multiply tenfold if I focus on them. Based on that, give me a concrete direction for the next year."

Why it works: instead of the general panic of "what about all this AI," you get a map. What to drop, because a machine will do it soon anyway. What to double down on, because that's where your effort multiplies. One strong model that sees the whole of your work can deliver that clarity in fifteen minutes.

Prompt #4 (the secret): draft your questions with a weaker AI first

There's one more trick almost nobody mentions. Since your time with a very strong model is limited, don't waste it polishing the question itself. Do that beforehand — with the regular model you have on hand all the time.

Sit down (or go for a walk and use voice mode) and just talk through your situation with the weaker AI: what you're working on, what's not working, what's stressing you, where you want to get. Then ask it one thing:

"In a moment I'll have brief access to a much smarter version of you. Based on everything I've told you — what exactly should I ask it to get the most out of that short time?"

You'll get a ready set of questions tailored to your situation. Then you walk into Fable 5 not with a blank mind, but with a list that actually moves the needle.

How to turn Fable 5 on

There's nothing to install or "activate." If you have a paid Claude plan (Pro, Max, or Team), Fable 5 is simply on the model list — on the web, in the mobile app, and on desktop. You pick it and write like always. Just remember two things: you can use it for up to half your weekly limit, and the free window runs until July 19.

If you don't have a paid plan, this is the week to consider one — because access to the most powerful model at the price of a normal subscription doesn't happen often and, as you can see, doesn't last long.

Want to run these prompts against your own actual business instead of guessing? Book a 30-min call — I'll show you which of the four questions matters most for you and how to turn the answers into real improvements.

Why this matters more than it looks

It's easy to file this under "trivia for tech fans" — another model, another name. But underneath it is something that touches every business.

A year from now, models of this class will be standard. They'll be in every subscription, the way a company email inbox is standard today. And "standard" is the situation where everyone has the same thing and nobody has an edge.

You have the edge now — in a short window where most of your competition either doesn't know Fable 5 is available or wastes it on trivia. Whoever uses it this week to rebuild their foundations — their working system, their security, their direction for the year — walks out of this window with something that keeps working long after the model leaves the plan.

This isn't a race for access to the technology. It's a race for who knows what to ask.

FAQ

What is Fable 5? An AI model built by Anthropic — the same company that makes Claude. It's described as their most powerful model. Because of compute limits, its availability is switched on and off periodically.

How much does it cost and how long is it free? Until July 19 it's available inside paid Claude plans (Pro, Max, Team) at no extra cost — up to 50% of your weekly limit. From July 20, every use is billed from a separate pool of paid credits, by usage, which is far more expensive.

Do I need technical skills to use this? No. You just need a paid Claude plan and to pick Fable 5 from the model list. You can copy and paste the prompts in this article with zero setup.

How is Fable 5 different from the regular AI chat I already use? Mainly in the quality of its reasoning on hard, complex problems. For simple tasks (email, translation, short text) you won't notice a difference, and a stronger model is overkill. Fable 5 pays off where you need genuinely deep analysis — an audit, strategy, a system rebuild.

What if I don't make it before July 19? Three of these four prompts are universal — they work on any strong model, even after the window closes. Fable 5 will simply answer them best. So if you have access now, it's worth doing this week.

Summary

For a few days you have the most powerful publicly available AI model within reach, at the price you already pay. Most people will waste it on trivia. You can use it on four things that stay: rebuilding your working system, a security audit, a map of your direction for the year, and learning to ask better questions in the future.

At Prospere AI we help companies do exactly that — turn access to strong models into concrete improvements that last for years, not a flashy one-day demo. If you want to run these prompts against your own business before the window closes: Book a 30-min call.

A year from now this will be standard. Today it's an edge. In exactly that order.

Sources: Anthropic — Claude Fable 5 and Mythos 5, BleepingComputer — Fable 5 free for paid users until July 19, Forbes — Claude Fable 5 Extends To July 19.