claude-fable-5.1

Claude Fable 5.1 is Anthropic’s frontier model for demanding reasoning and long-horizon agentic work. It excels at complex software development, code review, multi-step scientific research, knowledge work, and the creation of documents, spreadsheets, and presentations. With text-and-image input, always-on adaptive thinking, a 1-million-token context window, and up to 128K output tokens, it can maintain context across long unattended workflows, verify its own results, trace issues to their root c