Claude

Editor's Review

Claude's 5.5 lineup completed in early October 2026: Opus 5.5 (Sept 22), Sonnet 5.5 (Sept 28), and Haiku 5.5 (Oct 7). All three offer 1M-token context, 128K output, and June 2026 knowledge cutoff. API pricing: Opus 5.5 at $4/$20, Sonnet 5.5 at $2/$10, Haiku 5.5 at $0.10/$0.50 per million input/output tokens. Fable 5.1 and Mythos 5.1 (Sept 1, $10/$50) sit at the top for maximum capability, with Fable requiring 30-day data retention. The October 7 Sonnet 5.5 cache read price cut is significant for agent developers: prompt cache reads dropped from $0.20 to $0.10 per million tokens (0.05x base input price, down from 0.1x). Cache-heavy agent workflows—repeatedly loading the same instructions and files—just got materially cheaper. (Anthropic's own Claude Code displayed stale prices for two days; fixed in 2.1.296 on Oct 9.) Migration gotcha (Oct 15): upgrading from Opus 5/Sonnet 5 by only changing the model name triggers HTTP 400 on five settings. Google's Antigravity platform quietly added Opus 5.5 and Sonnet 5.5 on Oct 3 for paid AI Pro/Ultra subscribers; the old Claude 4.6 series retires November 2. Subscription pricing is unchanged: Pro at $20/mo or $200/year ($17/mo effective) remains the only major assistant with a real annual discount. Best for developers in the terminal (Claude Code), researchers with long documents, and writers wanting careful prose. Versus ChatGPT: Claude wins on coding and long-context reasoning; ChatGPT wins on multimodal breadth.