On Tuesday, Anthropic launched a new “Mythos-class” model, Fable 5, describing it as being more powerful than any other model the company had ever made generally available. It’s a significantly tamer version of Mythos, the behemoth model which Anthropic announced in April but has thus far withheld from the public due to its alleged sophistication at finding and exploiting cybersecurity vulnerabilities. If users ask Fable 5 about potentially sensitive subjects like cybersecurity, biology, chemistry, the company said, it will respectfully decline to respond, and instead automatically revert to an earlier model, Opus 4.8.
Almost immediately, users started complaining that Fable’s safety guardrails are too sensitive, refusing to answer sometimes comically harmless requests. Ask the model a question that you might see on a third-grader’s biology homework, for example, and it’s liable to take that as a red flag, as if you’re planning to build some biological doomsday weapon.
You’re not even allowed to ask Fable about basic biology questions, let alone anything that could potentially be dangerous. pic.twitter.com/FOlGpPJqsB
— Crémieux (@cremieuxrecueil) June 9, 2026
This hypersensitivity was built in by design, and Anthropic gave ample warning that this would lead a portion of benign prompts to be flagged as dangerous. “To release the model both safely and quickly, we’ve tuned these safeguards conservatively,” the company wrote in its blog post announcing the release of Fable 5, along with another, more powerful model with limited availability called Mythos 5. “With more capable models arriving in the coming months, we’re working to improve our safeguards and reduce false positives as quickly as we can.”
In a Reddit thread that kicked off a few hours after Fable’s release, complaints from developers about the model’s touchy safety mechanisms started piling up. “Completely unusable right now,” one Redditor wrote. “Hopefully [Anthropic] will chill on the guardrails in a week or two.” It’s an echo of similar criticism that recently started circulating online after Anthropic recently gave Opus 4.8 an “honesty” upgrade, making the model a little too unwavering in its commitment to the truth for some users’ tastes. In both cases, it’s a reminder that AI developers’ efforts to strike the perfect tone in their models’ communication styles is always going to alienate and annoy some people (hence the push towards more personalizable chatbots that we’ve been seeing from some big AI labs).
Burning through tokens
The ire that’s now being directed at Fable, however, is about more than the chatbot’s “personality.” It’s about money.
All those harmless prompts that Fable erroneously shoots down are still costing users precious tokens, and the price of those tokens is higher than ever: measured in both its inputs and outputs, Fable 5 costs twice as much as Opus 4.8.
In its announcement on Tuesday, Anthropic specifically positioned Fable as being an expert in longer, more “agentic” tasks. But as developers set the model loose on more intensive coding projects, some were unpleasantly surprised by how quickly they’ve been burning through the token-usage allowances provided by their subscription plans. “I was watching my usage tick up roughly 2% per minute. Not per hour. Per minute,” One Redditor who said they’re subscribed to the $200/month Max 20x plan wrote on Tuesday. “A long agentic session would chew through the entire [token-usage limit] window before lunch. For context I never came close to hitting limits with Opus 4.8 doing the same kind of work.”
Fable is available on the company’s Pro, Max, Team, and seat-based Enterprise plans at no extra cost, Anthropic said in its post on Tuesday. In other words, individual developers and teams subscribed to these plans now have access to Fable through the same token-limit windows they’re currently paying for, but—as the Redditor’s post above makes clear—those limits will be hit much faster due to Fable’s enormous compute demands.
The haves and the have-nots
Fable’s current subscription-based availability will be replaced by a “pay-as-you-go” pricing model starting June 23, according to Anthropic, meaning any developer or organization that wants to use Fable will need to start paying for usage credits.
That’s been stoking fears of an impending productivity gap between developers and companies with deep enough pockets to afford Fable’s (and its successor models’) industry-leading capabilities, and those with more modest budgets who will be forced to use cheaper, slower, more limited models. The concern is that once that gap starts to form between the haves and the have-nots, it will widen at a rate that’s equivalent to the evolution of the models themselves—exponentially, possibly. There will be an AI-powered superclass on the one hand, and a “permanent underclass” on the other.
“The permanent underclass everyone keeps tweeting about has a start date now: June 23,” one X user posted Tuesday night.
A similar argument has been fueling resentment against Anthropic for its so-called Project Glasswing, a program through which Mythos (think Fable without the guardrails) has been slowly and steadily deployed to groups of early testers, the idea being that by scaling slowly, the company can map out and prepare for the novel cybersecurity threats posed by the model. At least for some people, Project Glasswing is an early glimpse of a future in which access to the most powerful AI models is delegated exclusively to a small contingent of uber-wealthy organizations boasting the most state of the art cybersecurity systems. Again, everyone else (according to this view) will have to settle for watered-down alternatives like Fable 5.
But while it’s highlighted safety concerns as its primary reason for withholding Mythos to all but a relatively few customers, it’s likely that compute limitations are at least as important of a guiding factor behind Anthropic’s rollout strategy. Using models like Fable of course costs tokens for users, but it also costs the developers behind them for training (building new versions of the model) and inference (running existing models).
A sudden surge of developers using Fable for long-running, complex tasks like building entire websites could pose a legitimate compute bottleneck for Anthropic, making it necessary to roll it out in carefully measured stages. (In its announcement on Tuesday, the company said that “when sufficient capacity allows us to do so…we aim to restore Fable 5 as a standard part of subscription plans.”)
Seen in that light, the company’s upcoming switch to a pay-as-you-go model for Fable makes more sense. As one Redditor put it on Wednesday, “giving everyone unlimited access to the most expensive model makes about as much sense as giving every customer unlimited private jet flights because they paid for an airline membership.”
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