Anthropic Claude Fable 5.1

This developer-oriented analysis of Claude Fable 5.1 (dated September 3, 2026, two days after launch) walks through what actually changed for teams calling the model from scripts, agents, or content pipelines. It confirms the September 1, 2026 simultaneous release of Fable 5.1 and Mythos 5.1 as Anthropic's strongest op Beyond restating the launch facts, the post flags integration risks that press summaries omit, specifically that the migration guide contains breaking changes capable of silently disrupting existing integrations if developers do not read it. It positions Fable 5.1 against Fable 5, Claude Opus 5, and GPT-5.6 Sol, and no

Anthropic introduced Claude Fable 5.1 alongside Claude Mythos 5.1 on September 1, 2026, positioning them as the company's most advanced models for coding, long-running agentic work, and knowledge work. The two share the same underlying weights but differ in safeguards: Fable 5.1 is generally available to all users, whi Pricing changes center on caching rather than base tokens: Fable 5.1 keeps input at $10 per million tokens and output at $50 per million tokens, but cuts cache reads from $1.00 to $0.25 per million tokens, a 75 percent reduction. Anthropic's own benchmarks reported in this coverage show Fable 5.1 reaching 52.6 percent

Coursiv's launch coverage (September 1, 2026) provides a detailed specification table for Claude Fable 5.1: 1 million token context window, 128,000 token maximum output, text and image inputs with text output, adaptive thinking always-on at default high effort, June 2026 knowledge cutoff, and API model ID claude-fable- The benchmark comparison matrix shows Fable 5.1 outperforming Fable 5, Opus 5, and GPT-5.6 Sol across agentic scientific research (52.6% vs 24.7%/29.0%/22.4%), business workflows (31.4% on AutomationBench), and computer use (41.7% on OSWorld 2.0 strict). The article notes availability through Claude apps, Claude Code,

D-Central's launch-day analysis of Claude Fable 5.1 (September 1, 2026) reproduces Anthropic's benchmark table, highlighting that Fable 5.1 scored 73.4% on CursorBench 3.2.0 (vs Opus 5 at 70.0%), 55.8% on Terminal-Bench 4.0 (up from 42.0% for Fable 5), and 52.6% on Terminal-Bench-Science 0.1 (more than double Fable 5's The piece frames Fable 5.1 as a preview of capabilities that will eventually be replicated in open-weight local models, noting it remains proprietary. While the editorial framing is tangential to DigitalOcean's hosted endpoint, the verified benchmark figures provide useful context for developers evaluating the model's

OpenRouter's model catalog entry confirms that Anthropic's Claude Fable 5.1 was released on September 1, 2026 as a direct upgrade to Claude Fable 5, with the largest gains in agentic coding, long-running agentic workflows, and knowledge work — including long code refactors, front-end and visual code generation, and fin Because the subject is the Claude Fable 5.1 model itself, this candidate is treated as model-level reference material rather than gateway marketing: it directly names anthropic/claude-fable-5.1 and codifies the public capability framing and pricing baseline that developers evaluating the model on DigitalOcean's Gradien

BenchLM's profile for Claude Fable 5.1 records the model as released on September 1, 2026, tagged as proprietary with reasoning enabled and a 1M-token context window. The page compiles 25 source-displayable benchmark rows and gives Claude Fable 5.1 a capability score of 84.6/100, ranking it 1 of 232 in BenchLM's tracke Per-category percentiles on the BenchLM page show Claude Fable 5.1 at the 100th percentile for Agentic, Coding, and Knowledge, and 95th percentile for Reasoning; Math, Multilingual, Multimodal, and Instruction Following are marked "Not eligible" on this profile. Reported throughput is 66 tokens/second with a first-toke

Artificial Analysis published benchmark evaluation results for Claude Fable 5.1 on September 1, 2026, covering five adaptive reasoning effort configurations on what is tagged as the Default Fallback endpoint. Intelligence Index scores were recorded at 58 (Low Effort), 60 (Medium Effort), 62 (High Effort), 65 (Xhigh Eff This entry is directly relevant to developers using DigitalOcean's Gradient AI Platform inference endpoint for Claude Fable 5.1, as it provides independent composite benchmark data spanning the full reasoning-effort spectrum. The Default Fallback tagging suggests the DigitalOcean-hosted variant routes through a fallbac