Earlier this week, Anthropic released its most powerful public model yet: Claude Fable 5. This model is the "safe" version of an even more powerful model, Mythos, that Anthropic has yet to release to the public due to potential dangers.

Just days later, the Trump administration issued an export control directive barring the use of Fable 5 from foreign nationals. As a result, Anthropic was forced to disable Fable 5 for all its customers to comply with the order.

In a statement, Anthropic said it believed the order was issued by the U.S. government to use a method to "jailbreak" Fable 5 to identify vulnerabilities. Anthropic claimed in its statement that other AI models could do the same without a bypass. The company specifically named GPT 5.5, the latest AI model from its biggest competitor, OpenAI, as one such model.

There are currently too many unknown variables to determine if this is accurate. However, Mashable was preparing a piece comparing Anthropic's Claude Fable 4 and OpenAI's GPT 5.5 prior to the Trump administration's order.

It appears the U.S. government's concerns could be related to just how powerful Claude Fable 5 appears to be, even with its safeguards.

Here's how Fable 5 stacked up against GPT 5.5.

Claude Fable 5 vs GPT 5.5: Feature set

According to Anthropic, "Fable 5’s capabilities exceed those of any model we’ve ever made generally available." 

"It is state-of-the-art on nearly all tested benchmarks of AI capability, showing exceptional performance in software engineering, knowledge work, vision, scientific research, and many other areas," Anthropic says. "The longer and more complex the task, the larger Fable 5’s lead over our other models."

When GPT 5.5 rolled out in late April, OpenAI said that the model had improved on its "agentic coding, computer use, knowledge work, and early scientific research" capabilities.

Both are very similar when it comes to their feature set and stated purpose. These aren't images or videos. generation models. These are large language models used for document analysis, data interpretation, and advanced coding and development. Both are definitely competitors when it comes to use cases.

The difference between the two competing models will be how they perform.

Claude Fable 5 vs GPT 5.5: Leaderboards and benchmarks

On the popular Arena leaderboard, Fable 5 far and away leads all of the other AI models.

Claude Fable 5 currently sits at the top of the Arena leaderboard with Claude Opus 4.7 Thinking and Claude Opus 4.8 Thinking taking the second and third spots. The top three are all Anthropic's models, with OpenAI's GPT 5.5 coming in fourth. 

Fable 5 also leads in Artificial Analysis, Simple Bench, and practically every other leaderboard that has ranked the AI model.

According to Anthropic's own comparison chart, when it launched Fable 5, the AI model simply blows GPT 5.5 away across multiple benchmarks, from agentic coding and knowledge work to cybersecurity.

While it may be accurate that other models can also identify these alleged vulnerabilities, perhaps the U.S. government calculated that Claude Fable 5 was just too dangerously good at it based on the data.

Claude Fable 5 vs GPT 5.5: Availability and pricing

Before Anthropic pulled Fable 5 due to the U.S. government's order, Fable 5 was available to paid subscribers on Pro, Max, Team, and seat-based Enterprise plans at no additional cost until June 22. Anthropic planned to remove Fable 5 from these plans on June 23 and temporarily move to a usage-based paid add-on model until demand for Fable 5 dissipated. 

Fable 5 was priced on its Claude API and consumption-based Enterprise plans at $10 per million input tokens and $50 per million output tokens.

Fable 5 is no longer available for any of Anthropic's users.

OpenAI has made GPT 5.5 available to OpenAI Plus, Pro, Business, and Enterprise users in ChatGPT and Codex. Usage-based API pricing for GPT 5.5 starts at $5 per million input tokens and $30 per million output tokens.

GPT 5.5 is currently available for OpenAI's users.