Scheduled change
Anthropic’s October 30 notes deprecate fast mode for Claude Opus 4.8, with removal scheduled for November 30. After removal, requests to claude-opus-4-8 with speed: "fast" will return an error. This deadline concerns fast mode; no cutoff hour or timezone is stated. The notice does not establish a standard-speed shutdown date. [1]
The linked guide directs fast-mode users to Opus 5.5. It describes premium pricing, separate rate limits, and faster output tokens per second rather than quicker first-token delivery. The response’s usage.speed field identifies the speed used. [2]
Our take
Inventory affected model and speed combinations before changing them. Validate replacement behavior, capacity, and cost separately; a faster configuration still needs a deliberate migration check.