Claude Sonnet 5.5 is Anthropic's newest Sonnet, which Anthropic calls its best combination of speed and intelligence. For most people it is a strong default for real work on Magnus.
Released September 28, 2026 by Anthropic. Sonnet 5.5 has a 1M-token context window and adaptive thinking. API pricing is $2 per million input tokens and $10 per million output tokens - less than Sonnet 4.6.
On the All-inclusive plan a Sonnet 5.5 reply costs 3 credits, the same as Sonnet 4.6.
Daily driving: chat, documents, goals, charts, and the full Claude toolset - integrations, web search, PDFs. On a long, tool-heavy task it works quietly and then writes up the result.