Anthropic's Claude Sonnet 5.5 Rumored for Next Month with 2M Token Context

机器之心 · wechat · 2026-08-10

Anthropic's upcoming Claude Sonnet 5.5 (internally codenamed "Fennec") is reportedly in its final development stages and could launch as early as next month. Key upgrades: The context window will double from 1 million to 2 million tokens, featuring faster inference, lower latency, and significantly improved long-context reasoning, multi-step planning, and tool-calling capabilities (browser and terminal). Performance is said to approach the flagship Fable 5, while maintaining Sonnet-tier pricing.

Positioned against the highly cost-effective DeepSeek V4 Flash, Sonnet 5.5 aims to be the new value champion. With the Haiku line untouched for nearly a year, Anthropic may be shifting strategy to let Sonnet take over the lightweight model market to counter OpenAI's compact models.

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