Claude Fable 5 — reviews, specs & pricing

Anthropic's most capable widely released model, built for long-running agents. 1M-token context, 128k max output, always-on adaptive thinking. $10/$50 per 1M tokens.

Summary

Claude Fable 5 is Anthropic's premier model designed to power highly sophisticated, autonomous, long-running agents. It features a massive 1M-token context window, an unprecedented 128k maximum output, and always-on adaptive thinking for deep problem-solving. This makes it a formidable tool for complex programming, analysis, and conversational workflows.

Sample use case

An enterprise development team can use Claude Fable 5 to automate the refactoring of a massive legacy codebase. By ingesting the entire repository within its 1M-token context window, the model can autonomously identify structural inefficiencies, map out dependencies, and generate thousands of lines of updated, production-ready code in a single 128k output run.

Specifications

  • Provider: anthropic
  • License: closed
  • Context: 1000k tokens
  • Input price: $10/M tok
  • Output price: $50/M tok
  • Released: 2026-06-09

Pros

  • Massive 1M-token context window
  • Unprecedented 128k maximum output
  • Always-on adaptive thinking
  • Optimized for autonomous agents

Cons

  • Premium pricing at $10/$50 per 1M tokens
  • Higher latency during complex reasoning
  • Inefficient for simple query-response tasks

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Frequently asked questions

What is Claude Fable 5?

Claude Fable 5 is Anthropic's premier model designed to power highly sophisticated, autonomous, long-running agents. It features a massive 1M-token context window, an unprecedented 128k maximum output, and always-on adaptive thinking for deep problem-solving. This makes it a formidable tool for complex programming, analysis, and conversational workflows.

How much does Claude Fable 5 cost?

Claude Fable 5 costs $10 per million input tokens and $50 per million output tokens.

Is Claude Fable 5 open source?

Claude Fable 5 is released under the closed license.