New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run.
100
Coding
98
Writing
100
Research
90
Images
20
Value
99
Long Context
Use this when
Frontier agentic coding, long-horizon autonomous work, and agentic scientific research
Skip this if
You need low latency, or your workload is uncached and cost-sensitive — Claude Opus 5 is half the base price and within a few points on agentic coding.
Pricing
$10.00/1M in
$50.00/1M out
Context
1M tokens
Speed
Deliberate
Released September 1, 2026 alongside Claude Mythos 5.1, the first update to the Mythos-class line since Fable 5 on June 9. API ID claude-fable-5-1; generally available on the Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry. Published launch numbers (Fable 5.1 / Fable 5 / Opus 5 / GPT-5.6 Sol): Terminal-Bench-Science 0.1 52.6 / 24.7 / 29.0 / 22.4; Terminal-Bench 4.0 55.8 / 42.0 / 52.3 / 37.3; CursorBench 3.2.0 73.4 / 70.5 / 70.0 / 67.2; AutomationBench 31.4 / 17.1 / 26.9 / 19.6; OSWorld 2.0 strict 41.7 / 36.1 / 39.6; Humanity's Last Exam (no tools) 60.9 / 57.8 / 56.6; GDPval-AA v2 1853 / 1723 / 1824 / 1711. GDPval-AA v2 is rescaled from the v1 numbers quoted on the Fable 5 page and is not directly comparable to them.
Anthropic's new Mythos-class flagship and the most capable coding model anyone can use — 80.3% SWE-Bench Pro, an 11-point jump over Opus 4.8. 1M context, 128K output, native parallel subagents. Released June 9, 2026.
Verdict
Superseded by Fable 5.1 — still 80.3% SWE-Bench Pro, but 5.1 is better and cheaper to run.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Launched June 9, 2026 as the public, Mythos-class release. Available on the Claude API, Microsoft Foundry, and Google Vertex AI. Free for all users until June 22, 2026. Same underlying model as Claude Mythos 5, with safeguards that block specific high-risk cyber responses. Superseded by Claude Fable 5.1 on September 1, 2026 — same $10/$50 base pricing, cache reads cut from $1.00 to $0.25 per 1M tokens.
SWE-Bench Pro 80.3%Mythos-classParallel subagentsAgenticLong contextPremiumSuperseded
Best for
The hardest coding tasks, autonomous multi-step agents, and frontier-grade reasoning
Anthropic's newest Opus flagship — 69.2% SWE-Bench Pro, 88.6% SWE-Bench Verified, 1890 Arena Elo (121 pts ahead of GPT-5.5), and native parallel subagents. Same $5/$25 price as Opus 4.7.
Verdict
Best value premium coder — frontier-grade at half of Fable 5's price.
Quality score
97%
Pricing
$5.00/1M in
$25.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Launched May 27, 2026. Available on Claude API, AWS Bedrock, Google Vertex AI, Microsoft Foundry, and GitHub Copilot. Fast mode available at $10/$50 per 1M tokens.
CodingParallel subagentsAgenticLong contextPremiumBest value premium
Best for
Hardest coding tasks, parallel agentic workflows, and high-fidelity vision
Pricing moves, ranking shifts, and capability updates.
New ModelSep 1, 2026
Claude Fable 5.1 and Mythos 5.1 released — better on every published benchmark, and cheaper to run
Anthropic shipped Claude Fable 5.1 and Claude Mythos 5.1 on September 1, 2026 — the first update to the Mythos-class line since Fable 5 launched on June 9. Base pricing did not move ($10 in / $50 out per 1M tokens), but cache reads were cut 75%, from $1.00 to $0.25 per 1M. Anthropic puts the net effect at roughly 25% cheaper on typical workloads and up to 45% on heavily agentic ones — an upgrade that costs less than the model it replaces. The headline result is Terminal-Bench-Science 0.1, where Fable 5.1 scores 52.6% against Fable 5's 24.7%, Opus 5's 29.0% and GPT-5.6 Sol's 22.4%. It also leads Terminal-Bench 4.0 agentic coding (55.8% vs 52.3% for Opus 5), CursorBench 3.2.0 (73.4%) and AutomationBench (31.4%, nearly double Fable 5's 17.1%). Anthropic published no SWE-bench Verified or Pro figure at launch, so our SWE-bench leaderboard is unchanged; independent evaluator Vals AI ranks Fable 5.1 first of 51 models on its Vals Index, first on LiveCodeBench (90.5%) and first on MMLU Pro (92.4%). Mythos 5.1 is the same model with safeguards lifted, scores 60.9% on Terminal-Bench 4.0, and stays restricted to vetted US cybersecurity and life-sciences organisations. API ID claude-fable-5-1, generally available on the Claude API, Amazon Bedrock, Google Cloud and Microsoft Foundry. Every figure verified against Anthropic's launch numbers and two independent write-ups on September 1, 2026.
Claude Fable 5.1 is best for frontier agentic coding, long-horizon autonomous work, and agentic scientific research. It is a strong fit when that workflow matters more than the tradeoffs around premium pricing and deliberate speed.
When should I avoid Claude Fable 5.1?
You need low latency, or your workload is uncached and cost-sensitive — Claude Opus 5 is half the base price and within a few points on agentic coding.
What is a cheaper alternative to Claude Fable 5.1?
Grok 4.5 is the lower-cost option to compare first when you want a similar workflow fit with less token spend.
What is a faster alternative to Claude Fable 5.1?
Claude Fable 5 is the better pick when response time matters more than maximum depth or premium quality.
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