Claude 5 (Fable 5 / Opus 5 / Sonnet 5)
Anthropic's 2026 generation — four releases in under two months.
You're looking at an AI model record: who built it, what it can do, and the hardware and data behind it.
Anthropic opened its Claude 5 generation with Fable 5 (announced June 9, 2026): a new frontier tier above Opus with always-on adaptive thinking, a 1-million-token context window and 128K output tokens. Sonnet 5 followed on June 30 for agentic coding and knowledge work, and Opus 5 on July 24 — positioned as approaching Fable 5's intelligence at half the price, and the new default on the Max plan — Anthropic's fourth Claude 5 release in under two months. A restricted Mythos-class variant (Claude Mythos 5) shares Fable's underlying model and is available only to approved organizations. Parameters undisclosed.
Specifications & key facts
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Overview
How this connects to the rest of the stack
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Developed by
Trained on
Runs inference on
Benchmarked on
Successor to
Competes with
Sources
Anthropic — Introducing Claude Opus 5 ↗ · Axios on Opus 5 (Jul 2026) ↗
Record reviewed as of 2026-08-31 — see Methodology.