Dictionary term
Claude Model Tiers: Haiku, Sonnet, Opus, Fable
Also called Haiku · Sonnet · Opus · Fable · Mythos · Claude models
Anthropic's Claude models come in named tiers that trade capability against speed and cost: Haiku is the fastest and cheapest, for high-volume tasks like classification, extraction and routing; Sonnet is the balance of speed and intelligence; Opus targets long-running agentic coding and knowledge work and is the docs' suggested starting point for most workloads; Fable is for the most demanding reasoning and long-horizon agentic work. Mythos offers the same capabilities as Fable, restricted to organizations verified through Anthropic's verification programs; it is a restricted-access variant, not a tier above Fable.
In plain English
Claude comes in sizes: Haiku is the quick, cheap one, Sonnet is the everyday all-rounder, Opus is the strong default for serious work, and Fable is for the hardest jobs.
Analogy
Like shipping options: economy (Haiku) for quick cheap parcels, standard (Sonnet) for everyday deliveries, express (Opus) as the dependable default for important ones, and a specialist courier (Fable) for the hardest jobs.
Why it matters
Picking the right tier per task controls the cost and latency of automations that call Claude at scale.
In practice
A lead-handling automation uses Haiku to classify inbound messages, Sonnet to draft routine replies, and Opus or Fable only for multi-step research or coding; the current version and price of each tier lives in the model list, not in this definition.
Related terms
Sources
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