Claude Fable 5
A model in Anthropic's Claude series that offers certain features accessible to subscribers at no additional cost within their subscription.
Core Facts
Timeline (last 90 days)
Battle Drones is a Command & Conquer-style real-time strategy game; the early version was built with Claude Fable 5, and after Opus 5.5 took over, the gameplay experience changed qualitatively.
This incident did not disclose the specific distribution of error codes or the proportion of affected requests, nor did it state whether it was related to a particular region or calling method.
At 05:16 UTC the official first public notice was given with the status Investigating, and at 05:24 UTC the status was upgraded to Identified.
Officially, the fix was deployed at 05:41 UTC and the service entered the monitoring phase, and at 05:53 UTC it was formally marked as resolved.
The incident began at 22:00 Pacific Time on October 23 (05:00 UTC on October 24) and ended at 22:35 PT / 05:35 UTC, lasting about 35 minutes in total.
This performance degradation mainly affects API requests to Claude Fable 5, manifesting as elevated errors.
Claude Fable 5 experienced an elevated request error rate at 19:49 UTC on October 21.
The official status page marked this incident as "Investigating," the technical team is locating the root cause, and remediation measures have not yet begun.
Before the official root cause analysis is released, any speculation about the cause of the errors must be treated with caution.
Check whether existing monitoring covers the request success rate and latency of Claude Fable 5 to ensure anomalies are detected in time.
30 more timeline events
All Facts (20)
The core difference between Fable 5.1 and Mythos 5.1 lies in the depth of safety measures, not in the underlying capability level.
75%UnverifiedBattle Drones is a Command & Conquer-style real-time strategy game; the early version was built with Claude Fable 5, and after Opus 5.5 took over, the gameplay experience changed qualitatively.
50%UnverifiedThis incident did not disclose the specific distribution of error codes or the proportion of affected requests, nor did it state whether it was related to a particular region or calling method.
50%UnverifiedThe incident began at 22:00 Pacific Time on October 23 (05:00 UTC on October 24) and ended at 22:35 PT / 05:35 UTC, lasting about 35 minutes in total.
50%UnverifiedThis performance degradation mainly affects API requests to Claude Fable 5, manifesting as elevated errors.
50%UnverifiedOfficials have not yet disclosed the specific error types, affected regions, or proportion of users.
50%UnverifiedFor production environments that depend on Claude Fable 5, it is recommended to temporarily add retry logic or switch to a backup model to reduce the impact on end users.
50%UnverifiedCheck whether existing monitoring covers the request success rate and latency of Claude Fable 5 to ensure anomalies are detected in time.
50%UnverifiedBefore the official root cause analysis is released, any speculation about the cause of the errors must be treated with caution.
50%UnverifiedThe official status page marked this incident as "Investigating," the technical team is locating the root cause, and remediation measures have not yet begun.
50%UnverifiedThe project started in July, initially using Claude Fable 5, later upgraded to Opus 5.5, and was completed almost entirely in Claude Code for Web.
50%UnverifiedIn OpenRouter traffic from August 22 to September 20, 2025, the ratio of uncached input tokens to output tokens was 16.29x for Claude Fable 5 and 14.64x for GPT-6 Astra, with input costs accounting for about 75% of total cost.
50%UnverifiedOpenAI GPT-6 Astra and Anthropic Claude Fable 5 have the same official list price of $10.00/$50.00.
50%UnverifiedAnthropic's product line spans from Claude Haiku 5.5 ($0.06/$0.15) to Claude Fable 5 ($3.00/$15.00), a range of about 50 times.
50%UnverifiedIn the LSCBench leaderboard, Claude Fable 5 within Claude Code has a functional pass rate of 91.1% and a functional+security pass rate of 25.1%, the highest security pass rate among the six models.
50%UnverifiedClaude Fable 5 is backed by Anthropic's accumulated expertise in long context and safety alignment.
50%UnverifiedTom Tunguz found that 84% of tokens on OpenRouter flow to non-state-of-the-art models, and six models offering about 77% of frontier performance at 2.5% of Claude Fable 5's price carry the vast majority of usage.
50%Unverifiedv3.0.70 fixes a 400 error triggered when generating commit messages and executing tasks in reasoning-off mode, affecting models including GPT-6 Astra, GPT-6.1 Sol, Claude Fable 5, and Claude Opus 5.5.
50%UnverifiedClaude Fable 5 and Opus 5.5 do not support disabling thinking; sending thinking: {type: "disabled"} returns the error "thinking.type.disabled" is not supported for this model.
50%UnverifiedClaude Fable 5 is not a product name officially known to be from Anthropic.
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