Claude Sonnet 5

Anthropic's mid-tier reasoning model with a 1 million token context window, released in June 2026 as a step between Opus and Fable.

Strengths

Balances reasoning capability with efficiency across a wide range of tasks including analysis, coding, and creative work.

Best for

General-purpose work that requires solid reasoning and long-context handling without the overhead of flagship models like Opus or Fable.

Limitations

Less capable on complex multi-step reasoning and agentic work than Opus 5 or Fable models; not suited for the hardest reasoning tasks where Opus 5.5 or Fable 5.1 would be required.