Fable 5.1
- TYPE
- Model
- SIGNALS
- 7
- FIRST SEEN
- Sep 1, 2026
- LAST SEEN
- Oct 12, 2026
Recent signals
- Anthropic says new measures like preserved thinking in Fable 5.1 and Opus 5.5 have reduced data harvesting through distillation attacks by about 90% to 99% (Anthropic) Oct 12, 2026
- Anthropic says Opus 5.5 matches Fable 5.1 "on most tasks" while costing about 40% less to run than Opus 5; Opus 5.5 costs $4/1M input and $20/1M output tokens (Matthias Bastian/The Decoder) Sep 22, 2026
- Artificial Analysis Coding Agent Index: GPT-6 Astra scored 67, roughly equal to Claude Opus 5, Fable 5, and Muse Spark 1.3, but trailing leader Fable 5.1's 70 (Artificial Analysis) Sep 4, 2026
- Anthropic’s new Fable release is cheaper, less restrictive Sep 1, 2026
- Anthropic says Fable 5.1 sets new standards on coding, knowledge work, and long-running problem-solving tasks, and can fix the root causes of software issues (Carl Franzen/VentureBeat) Sep 1, 2026
- Anthropic says Fable 5.1 will cost an estimated 25% less than Fable 5 for typical workloads and up to 45% less for highly agentic work (Rachel Metz/Bloomberg) Sep 1, 2026
- Anthropic Says New Fable 5.1 AI Model Is Cheaper, Better at Coding Sep 1, 2026