MDL-1633 EST.2026 · IDX.264 Language model In production ⇄ Compare
Claude Fable 5 Anthropic · USA · 2026
Anthropic's most intelligent generally available model — the first of the Mythos-class tier above Opus.
Claude Fable 5 opens Anthropic's Claude 5 family and a new Mythos-class tier that sits above Opus in capability. It excels at long-horizon agentic work, software engineering and nuanced writing, with additional safety measures for dual-use capabilities. Its sibling, Claude Mythos 5, shares the same underlying model but is available only to approved organizations.
#frontier #agentic #coding #Mythos-class
Official website ↗ ▸ SpecificationsClass & identity
Model class Frontier LLM (Mythos-class)
Version / release Claude 5 family, 2026 Architecture
Architecture Transformer (frontier)
Parameters —
Context window 1,000,000 tokens · output: 128,000 tokens (Messages API); up to 300,000 via Message Batches API beta
Modalities Text, vision → text
Knowledge cutoff / data — Performance (benchmarks)
MMLU —
GPQA Diamond —
SWE-bench —
MATH / AIME —
Chatbot Arena Elo —
Domain benchmark — Capabilities Text Vision Function calling Computer use Extended reasoning Long context (≥200k) Multilingual Agentic coding
Reasoning mode Hybrid (standard + extended thinking)
Tool use / agentic Function calling, computer use, MCP, agentic
Multilinguality Multilingual
Key strengths Agentic coding, long-horizon reasoning, nuanced writing Access & deployment
Availability Proprietary API
License Proprietary
Pricing $10 / 1M input tokens, $50 / 1M output; prompt caching $12.50 (5 min) / $20 (1 h) write, $1 cache read
Deployment API / cloud
Safety / alignment Enhanced dual-use safeguards Compiled to the wujec.ai Spec Standard v1 — “—” means not publicly disclosed.