Fable 5
A competing model positioned against GPT-5.6 Sol. On the Agent Ultimate Exam benchmark, it scores 13.1 points lower than GPT-5.6 Sol.
Core Facts
Timeline (last 90 days)
Anthropic's three steep jumps in merge volume correspond respectively to the releases of Fable 5 and Mythos 5 (June 9), Opus 5 (July 24), and Fable 5.1 and Mythos 5.1 (September 1).
Simon Willison's analysis suggests that the internal enablement of the Fable and Mythos series models was the key catalytic factor in Anthropic's leap in coding speed.
When orchestrator Fable provided instructions containing an error, the Quen small model did not follow them blindly but instead implemented the correct behavior based on how real instruments actually work.
During the orchestration experiment, the entire build process had approximately 30 substantive defects, which were resolved across four rounds of fixes with none remaining in the final version, all of which were discovered through external validation and never proactively detected by the model itself.
The version orchestrated by Fable 5, which only provided guidance without modifying code, achieved more realistic physics and control logic; Fable itself changed only one or two lines of code, with nearly all code written by Quen, and the final product quality was noticeably better.
In an SVG simulation test for generating a payment card transaction completion animation, Gemini 4 Argon outperformed Fable 5.
Sol scored 68.8% in the coding test, close to the previous-generation Fable 5's 69.9%, but with a per-task cost approximately 80% lower.
Luna scored 66.6% in the coding test, with costs 93% and 96% lower than Opus 5 and Fable 5, respectively.
The video author judges Grok 4.7 to be roughly close to the level of Fable 5, but not quite reaching Fable 5.1.
An Anthropic Pro subscriber posted on the Reddit community, stating that their Pro account showed a new quota related to Fable 5.
40 more timeline events
All Facts (20)
The API model identifier for GPT-6 Astra is gpt-6-astra.
90%VerifiedAccounting for real usage scenarios, the actual cost advantage of Opus 5 over Fable is approximately 20% to 25%, with Fable costing about $2.75 per task and Opus 5 about $2.03.
65%UnverifiedFable 5.1 has stronger coding capabilities.
60%UnverifiedGrok 4.6's score on the Deep Suite benchmark improved from 54% to 66%.
60%UnverifiedFor small and medium-sized projects, it is already difficult to perceive a notable difference between Fable 5 and Sol compared to the previous generation Opus 4.8 and GPT 5.5, so AI models do not need to be maxed out.
60%UnverifiedSimon Willison's analysis suggests that the internal enablement of the Fable and Mythos series models was the key catalytic factor in Anthropic's leap in coding speed.
50%UnverifiedAnthropic's three steep jumps in merge volume correspond respectively to the releases of Fable 5 and Mythos 5 (June 9), Opus 5 (July 24), and Fable 5.1 and Mythos 5.1 (September 1).
50%UnverifiedDuring the orchestration experiment, the entire build process had approximately 30 substantive defects, which were resolved across four rounds of fixes with none remaining in the final version, all of which were discovered through external validation and never proactively detected by the model itself.
50%UnverifiedThe version orchestrated by Fable 5, which only provided guidance without modifying code, achieved more realistic physics and control logic; Fable itself changed only one or two lines of code, with nearly all code written by Quen, and the final product quality was noticeably better.
50%UnverifiedIn an SVG simulation test for generating a payment card transaction completion animation, Gemini 4 Argon outperformed Fable 5.
50%UnverifiedLuna scored 66.6% in the coding test, with costs 93% and 96% lower than Opus 5 and Fable 5, respectively.
50%UnverifiedSol scored 68.8% in the coding test, close to the previous-generation Fable 5's 69.9%, but with a per-task cost approximately 80% lower.
50%UnverifiedThe video author judges Grok 4.7 to be roughly close to the level of Fable 5, but not quite reaching Fable 5.1.
50%Unverified"Fable 5" is not a common name in Anthropic's publicly known product line.
50%UnverifiedThe entire project ultimately consumed approximately 2 billion tokens, with Fable 5 and Opus 5 each using about 800 million, Codex close to 400 million, and GROK using 76 million.
50%UnverifiedFable 5 is an AI product designed for creative writing or role-playing scenarios.
50%Unverified"Fable 5" does not correspond to any currently mainstream and known large model product.
50%UnverifiedIn the task of a robotic arm grasping blocks into a bowl, Fable 5 had a success rate of 5%, Fable 5.1 reached 40%, and GPT-6 Astra achieved 95%.
50%UnverifiedOpus 5 achieved a 26% pass rate on the enterprise automation benchmark, higher than Fable's 17.4%.
50%UnverifiedThe cost for Opus 5 to generate the AirLens website was 69 cents, compared to 94 cents for competitor Fable 5.
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