Claude Fable 5.2 and Mythos 5.2: What Changed

4 min read

Last updated November 10, 2026

Anthropic released Claude Fable 5.2 and Claude Mythos 5.2 on November 9, 2026. It calls them its most capable models, with faster replies and lower prices.

Key Points

Fable 5.2 is open to all users, while Mythos 5.2 is limited to vetted organizations.
Anthropic says both models write answers up to 30 percent faster than the 5.1 versions.
Fable 5.2 costs less to use through the developer platform than Fable 5.1 did.

Good to know. Anthropic still suggests most people start with Claude Opus 5.5. It recommends Fable or Mythos for the hardest technical work.

What Anthropic Released

Anthropic announced the models on its newsroom as its most capable tools for daunting technical work. Both are now part of the Claude family.

Fable and Mythos share the same underlying model, according to the official announcement. The difference is who can use them and how they are guarded.

Model	Who can use it	Main difference
Claude Fable 5.2	All users	Strong safety guards for cyber and biology topics
Claude Mythos 5.2	Vetted organizations only	Access through verification programs

Claude Fable 5.2 vs Mythos 5.2

Fable 5.2 has stronger safeguards around cybersecurity and biology. That makes it suitable for the general public.

Mythos 5.2 goes to organizations in two verification programs. One covers cybersecurity work, and the other covers life sciences research.

Enterprise customers can also reach Mythos 5.2 through a product called Claude Security. Anthropic says that tool runs on the new model.

What Got Better

Anthropic says the new models improve in coding, reasoning and vision. Testers also said they communicate more clearly than earlier versions.

Speed is the headline change. Anthropic says output arrives up to 30 percent faster than with Fable 5.1 and Mythos 5.1.

The company also reports that Fable 5.2 blocks requests less often. It says blocks dropped about 55 percent compared with Fable 5.1.

30%How much faster the new models produce output than the 5.1 versions, according to Anthropic.

Benchmark Results

Benchmarks are standard tests that compare models. Anthropic shared these scores for Fable 5.2 against Claude Opus 5.5.

Test	Fable 5.2	Opus 5.5
FrontierSWE v2, coding	69.9%	62.3%
FrontierCode 2.0, coding	49.1%	45.5%
Humanity’s Last Exam with tools	74.2%	67.7%
OSWorld 2.1, computer use	89.3%	87.2%

These figures come from Anthropic itself. Independent testing may show different results over time.

What do you mostly use chatbots for?

Writing and emails
Coding
Research and study
Not sure

Fable 5.2 Price for Developers

Developers pay per token, which is a small chunk of text. Yahoo Finance reported that the price dropped from Fable 5.1.

Option	Input, per million tokens	Output, per million tokens
Fable 5.1	$10	$50
Fable 5.2	$8	$40
Fable 5.2 fast mode	$16	$80

Anthropic says the optional fast mode speeds up output by up to 2.5 times. Prices can change, so check the official page before you build.

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Where You Can Use It

The Claude apps and the Claude developer platform.
Amazon Web Services, Google Cloud and Microsoft Azure.
Claude Code, which supports the new fast mode.

Anthropic says subscribers on eligible plans get extra Fable usage for a limited time. Our list of essential Claude Code commands can help coders get started.