Claude Opus 5.5 (Fast) is a speed-tuned variant in Anthropic's new Claude 5.5 family, positioned as the first release in that lineup and aimed squarely at agentic coding, long-running agent tasks, knowledge work, communication, and vision. According to Anthropic's launch announcement as reported by independent coverage, the model is described as a step-change improvement over Opus 5, producing output more than 30% faster than its predecessor while being more token-efficient per completed task. The "Fast" designation layers an additional speed mode on top of that base profile, reportedly delivering up to 2.5x faster generation in supported environments compared with the standard Claude Opus 5.5 tier.
Beyond raw speed, Claude Opus 5.5 (Fast) is framed by Anthropic as matching its larger Fable 5.1 sibling on most workloads while costing roughly the listed price% less per completed task than Opus 5, signaling a focus on practical efficiency for production agents rather than chasing peak capability at any price. Its very large context window and high output ceiling make it well suited to multi-step coding sessions, document-heavy reasoning, and tool-using workflows where the model needs to keep large codebases, transcripts, or retrieved evidence in view across many turns. For teams already standardizing on Anthropic models, the Fast variant offers a way to trade a small premium for markedly quicker iteration loops on agentic pipelines without leaving the Claude family.
