Claude Haiku 5.5 becomes the default fast model

Anthropic released Claude Haiku 5.5 on October 7, and it reached General Input on October 8. It replaces Haiku 4.5 everywhere, and it's the first Haiku to be a default agent model rather than opt-in, so specialists can run on it. It appears in the model picker, the hosted API catalog, and the Subscription group when you connect a Claude plan through Token Tunnel. See the models page.

How it works

• The model. A 1M-token context window (Haiku 4.5 had 200K) and adaptive thinking with an effort setting that defaults to medium. Anthropic lists it at $0.10 input and $0.50 output per million tokens for prompts up to 100K tokens, and five times that above.
• Saved selections move over. Any workflow, specialist, or setting that named Haiku 4.5 now runs on Haiku 5.5.
• Auto, hosted. The Fast tier now tries Claude Haiku 5.5 first, then GPT-6 Luna, Gemini 3.8 Flash, and Grok 4.7.
• Auto on your subscriptions. When Auto can use a model you've connected through Token Tunnel, each tier now runs one class above its hosted counterpart, because subscription usage isn't billed per token: Fast uses Claude Sonnet 5.5 or GPT-6.1 Sol, Balanced uses Opus 5.5 or GPT-6 Astra.

Also shipped

• A connected device that only serves Haiku 4.5 is no longer presented as Haiku 5.5.