Claude Fable 5.2

• 📏 One-million-token context window in Anthropic's Fable tier
• 🧠 Reasoning, vision, coding, function calling and web search
• 🔧 Built for agentic, long-horizon coding and tool-using workflows
• 👁️ Vision input alongside long-document and large-codebase reasoning
• 🆕 Successor to Fable 5.1 in Anthropic's top Claude tier
• 🏢 Mythos 5.2 variant mirrors its specs for verified organizations
• 🔒 Requires 30-day data retention; zero-retention only if authorized
• 🗓️ Released November 9, 2026 by Anthropic

Anthropic

Anthropic PBC is an American artificial intelligence company headquartered in San Francisco. Structured as a public benefit corporation, the lab develops large language models under the Claude name, with a research emphasis on building reliable, steerable,…

Claude Fable 5.2 is Anthropic's November 2026 release in the Fable line, the company's top-end Claude tier for demanding reasoning and long-horizon agentic work. It carries forward the family's defining specification: a one-million-token context window, letting it ingest entire codebases or book-length document sets in a single pass. Catalog capabilities span reasoning, vision, code-oriented work, function calling and web search.

The Fable line began with Claude Fable 5 in mid-2026, documented by Anthropic as a model for complex knowledge work and coding with sustained autonomous operation, planning across stages, delegation to sub-agents and self-verification of its work. Claude Fable 5.1 followed in the same tier later that year. Anthropic's own Claude Code documentation positions Fable models as the most capable options available there, suited to tasks larger than a single sitting, with longer autonomous sessions and more verification than the smaller Claude models.

Fable 5.2 continues that trajectory as the current head of the family. As a covered model it requires 30-day data retention and is not offered under zero data retention without explicit authorization, and a parallel Mythos 5.2 release shares its specifications for organizations cleared through Anthropic's verification programs. Within the broader Claude range, Anthropic's Claude Code documentation describes Fable models as intended for larger-scope, longer-running tasks than the Sonnet and Haiku options. Readers evaluating it against siblings such as Claude Opus 5.5, Claude Sonnet 5.5 or Claude Haiku 5.5 should consult Anthropic's model documentation for current per-model limits.