Anthropic launches Claude Sonnet 5 with near-Opus 4.8 performance

Sonnet 5 is priced at $3/$15 per million tokens (promo $2/$10 through Aug 31), close to its introduction rate, but uses a new tokenizer that increases token count ~30% for English. The model features a 1M token context window, 128K max output, and adaptive thinking enabled by default.