Claude Sonnet 5 Shifts to Standard Rates Effective September 1, 2026

Anthropic's promotional introductory pricing for Claude Sonnet 5 expired on August 31, resetting to standard enterprise rates of $3 per million input tokens and $15 per million output tokens. In multi-agent pipelines where iterative tool execution multiplies token volumes by 5x to 30x, teams that relied on intro pricing face sudden monthly invoice spikes. Engineering leaders are implementing prompt-prefix caching and small-model routing to control recurring inference expenditures.