Claude Fable 5

Overview

Anthropic's most capable widely released model, built for the most demanding reasoning and long-horizon agentic work, with always-on adaptive thinking. It includes safety classifiers that can decline high-risk requests, with fallback to other Claude models.

Generally available since June 9, 2026 on the Claude API, Claude Platform on AWS, Amazon Bedrock, Google Cloud and Microsoft Foundry. Shares specs with the invitation-only Claude Mythos 5 offered under Project Glasswing.

Key Specs