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Anthropic has released Fable 5 and Mythos 5

Emerging tech and AI2 min readSam Page

Anthropic has released Fable 5 and Mythos 5, available until June 22nd at no extra cost for paid plans. If you're using Claude Code, now is the time to try it out.

According to Anthropic, Fable 5 coding ability jumps from 69.2% to 80.3% compared to Opus 4.8.

That's a 16% increase in capability.

However, early reports state it uses twice the number of tokens as Opus 4.8.

Expect to burn through your usage quickly.

You can switch to it by typing "/model claude Fable 5".

Or select it from the model dropdown box in the Claude desktop app.

Anthropic also released Mythos, it's highly anticipated model which, according to them, has the "strongest cybersecurity capabilities of any model in the world."

It's worth noting, results have been replicated by experts using smaller models.

It's only been available to the US government and a selection of companies up until now, and they state is has been released with additional safe guards in place.

More on Mythos to follow...

We'll be starting full testing of Fable 5 / Mythos 5 today at 7DOTS and will follow up with early results in due course.

Keen to hear any early results you are seeing!

Benchmark report from Anthropic with following footnote:

Reported scores are within a 1-3 percentage point difference for Claude Mythos 5 and Claude Fable 5. This table shows the higher score of the two. Starred (*) benchmarks show a larger difference due to our blocking safeguards for cybersecurity and biology-related questions. For these benchmarks, Claude Fable 5 performs closer to Claude Opus 4.8 due to fallbacks.

First published on LinkedIn.

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---
title: "Anthropic has released Fable 5 and Mythos 5"
url: https://sam-page.com/thinking/anthropic-has-released-fable-5-and-mythos-5
date: 2026-06-10
author: Sam Page
type: Post or article
categories: [Emerging tech and AI]
reading_time: 2 min
summary: "Anthropic has released Fable 5 and Mythos 5, available until June 22nd at no extra cost for paid plans. If you're using Claude Code, now is the time to try it out."
first_published: https://www.linkedin.com/feed/update/urn%3Ali%3Ashare%3A7470377015678808065
---

# Anthropic has released Fable 5 and Mythos 5

Anthropic has released Fable 5 and Mythos 5, available until June 22nd at no extra cost for paid plans. If you're using Claude Code, now is the time to try it out.

![](https://sam-page.com/img/thinking/anthropic-has-released-fable-5-and-mythos-5-li1.webp)

According to Anthropic, Fable 5 coding ability jumps from 69.2% to 80.3% compared to Opus 4.8.

That's a 16% increase in capability.

However, early reports state it uses twice the number of tokens as Opus 4.8.

Expect to burn through your usage quickly.

You can switch to it by typing "/model claude Fable 5".

Or select it from the model dropdown box in the Claude desktop app.

Anthropic also released Mythos, it's highly anticipated model which, according to them, has the "strongest cybersecurity capabilities of any model in the world."

It's worth noting, results have been replicated by experts using smaller models.

It's only been available to the US government and a selection of companies up until now, and they state is has been released with additional safe guards in place.

More on Mythos to follow...

We'll be starting full testing of Fable 5 / Mythos 5 today at 7DOTS and will follow up with early results in due course.

Keen to hear any early results you are seeing!

---

Benchmark report from Anthropic with following footnote:

Reported scores are within a 1-3 percentage point difference for Claude Mythos 5 and Claude Fable 5. This table shows the higher score of the two. Starred (*) benchmarks show a larger difference due to our blocking safeguards for cybersecurity and biology-related questions. For these benchmarks, Claude Fable 5 performs closer to Claude Opus 4.8 due to fallbacks.