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Claude Mythos is Finally Here.

After months of speculation and hype, Anthropic has pulled back the curtain on what they call «Mythos class» models — but not quite in the way many expected. Two models have been released simultaneously: Claude Fable 5, available to the general public, and Claude Mythos 5, restricted to government partners and cyber defenders through Project Glasswing. The catch? Fable 5 is essentially Mythos 5 with cyber safeguards in place, priced at double the cost of Opus. And in a move that caught many users off guard, Anthropic is only offering Fable 5 through subscription plans until June 22nd, after which users will need to pay per token. The question is: does Fable 5 deliver on the promise, or is it just a safety-constrained preview of the real power locked behind Glasswing?

Nate Herk | AI AutomationTech1 Persone menzionate4 Termini del glossario
Durata del video: 8:41·Pubblicato 9 giu 2026·Lingua del video: English
4–5 min di lettura·2,029 parole pronunciateriassunto in 855 parole (2x)·

1

Punti chiave

1

Fable 5 and Mythos 5 are identical models under the hood; Fable simply has cyber safeguards in place while Mythos is unrestricted and available only to government partners and cyber defenders.

2

Pricing is $10 per million input tokens and $50 per million output tokens — double the cost of Opus — but Fable 5 is included in Pro Max, Team, and Enterprise subscriptions until June 22nd.

3

Performance benchmarks show dramatic improvements over Opus 4.8, particularly in agentic coding, knowledge work, vision tasks, and cyber security capabilities.

4

Anthropic is removing Fable 5 from subscription plans on June 23rd due to compute costs and capacity constraints, with no clear timeline for when it will return.

5

The release validates earlier predictions that Mythos capabilities would be «quietly baked into» public models like Opus rather than released under the Mythos name for general use.

In breve

Claude Fable 5 represents a significant capability jump over Opus 4.8, especially in coding and knowledge work, but it's not the full «Mythos» experience — that remains locked behind government partnerships. With only two weeks of free access through subscriptions, users should experiment heavily before June 22nd when token-based pricing kicks in.


2

Two Models, One Engine: Fable vs. Mythos

Fable 5 and Mythos 5 are identical models with different safeguards.

FABLE 5
Public Model with Cyber Safeguards
Available to all users today through Pro Max, Team, and Enterprise subscriptions until June 22nd. Priced at $10 per million input tokens and $50 per million output tokens — double the cost of Opus. Includes cyber security safeguards to prevent malicious use while maintaining strong performance across knowledge work, coding, and vision tasks.
MYTHOS 5
Unrestricted Model for Glasswing Partners
Identical to Fable 5 under the hood but with all cyber safeguards lifted. Restricted to US government partners, cyber defenders, and infrastructure providers through Project Glasswing. Offers the strongest cyber security capabilities of any model in the world but requires trusted access program approval.

3

Predicted It: The Mythos Rollout Strategy

Earlier predictions about Mythos capabilities being quietly integrated proved accurate.

A public model that you can just log in and use called Mythos? I don't think that's happening anytime soon. And it might not ever happen under that name, at least not the way that we're picturing it right now. I mean, they kind of told us the plan. A leak doesn't change the plan. So, I mean, everyone waiting for a big Mythos button to show up in the app next week, I think they're going to be waiting a while. So what do I actually think happens? I think the capabilities start to show up but kind of quieter. You know, I think the stuff that makes Mythos Mythos, the stuff that makes it so special, those features sort of start to get baked into future versions of Opus.

Speaker/Narrator


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Performance Benchmarks: Major Leaps Over Opus 4.8

Fable 5 shows substantial improvements across coding, knowledge work, and vision.

Pricing vs. Opus
2x (double)
Fable 5 costs $10 per million input tokens and $50 per million output tokens, compared to Opus pricing
Mythos Preview Pricing Comparison
5x cheaper
Claude Mythos preview released in April was five times as expensive as Opus; Fable 5 is only twice as expensive
Agentic Coding Performance
Major jump on Frontier Code
Significant improvement over Opus 4.8 on complex coding benchmarks, though SW-Bench Pro credibility questioned
Knowledge Work Capability
Big jump
Substantial improvement in analytical tasks and general knowledge work compared to Opus 4.8

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The June 22nd Deadline: Limited Free Access Window

Fable 5 leaves subscription plans in two weeks due to capacity.

⚠️

The June 22nd Deadline: Limited Free Access Window

Anthropic is removing Fable 5 from Pro Max, Team, and Enterprise subscription plans on June 23rd, forcing users to pay per token after that date. The company cites compute costs and capacity constraints — unsurprising given they recently filed to go public and are not yet profitable. They promise to restore Fable 5 to subscription plans «as quickly as we can» once sufficient capacity allows, but no timeline is provided.


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Agent Loops and Token Costs: A Word of Caution

🔁
Extended Autonomy
Fable 5 can work autonomously for much longer than previous Claude models, enabling more complex agentic workflows and reasoning chains.
💸
Token Usage Trap
Be cautious about open-ended agent loops. Most general knowledge work doesn't require continuous looping, and you risk hitting session limits quickly with aggressive automation.
🎯
Use Case Fit
Evaluate whether your task truly benefits from multi-agent loops or if a single well-crafted prompt will suffice. Model makers benefit from higher token usage, so apply critical thinking.

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Persone

Speaker/Narrator
Content Creator/AI Analyst
host

Glossario
Mythos ClassA tier of Claude models that sit above Opus in capability, starting with Claude Mythos preview and now including Fable 5 and Mythos 5.
Project GlasswingAnthropic's program for deploying advanced models with reduced safeguards to trusted partners, primarily US government agencies and cyber defenders.
Agentic CodingAI models performing coding tasks autonomously over extended periods, including debugging, refactoring, and implementing complex features without continuous human input.
Cyber SafeguardsRestrictions built into AI models to prevent their use in malicious cyber security activities, such as developing exploits or breaking security systems.

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