Anthropic announced on October 30 that fast mode for Claude Opus 4.8 is deprecated and will be removed on November 30, 2026. After that date, API requests using claude-opus-4-8 with speed set to fast will return an error. Anthropic recommends migrating to claude-opus-5-5 to retain fast mode, which is available on the Claude API and supported cloud platforms.
Fast mode runs a model with a faster inference configuration, without changing its intelligence or capabilities, according to Anthropic. The published fast-mode rates for Opus 5.5 are $8 per million input tokens and $40 per million output tokens, before applicable pricing modifiers. That compares with $10 and $50, respectively, for Opus 4.8 fast mode. The announcement concerns this accelerated mode, rather than retirement of the entire Opus 4.8 model.
Source · platform.claude.com ↗
