Claude Code · Anthropic · Claude · Mythos · Decrypt
Some of the appetite for this release was already primed
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Developers spent weeks this spring discussing how Anthropic let Opus 4.6 quietly lose its edge—dubbed AI shrinkflation, citing dropped capabilities—and Anthropic denied intentionally degrading any model.
Key facts
- Anthropic set the $2/$10 introductory rate to make that switch close to cost-neutral through August 31, after which price reverts to the standard $3/$15 Sonnet has charged
- On SWE-bench Pro—a coding benchmark pulling problems from actively maintained repositories with multi-file changes, scored as percent solved—Sonnet 5 hit 63.2% against Sonnet 4.6's 58.1%
- On GDPval-AA v2, an Artificial Analysis benchmark that scores real-world professional tasks across 44 jobs via blind pairwise Elo ratings, it landed at 1,618, a statistical tie with Opus 4.8's 1,616
- Fable 5 and Mythos 5 remain suspended for foreign nationals since June 12 under a U.S. export control directive tied to a disputed jailbreak finding
Summary
Anthropic launched Claude Sonnet 5 on Tuesday at $2 per million input tokens and $10 per million output tokens through August 31, after which pricing reverts to $3/$15—still a fraction of Opus 4.8's $5/$25 rate. On Anthropic's own evaluations, Sonnet 5 is virtually tied Opus 4.8 on the GDPval-AA v2 knowledge-work benchmark. Sonnet 5 ships with no special restrictions while Fable 5 and Mythos 5 remain suspended for general usage under a June 12 export control directive. Anthropic released Claude Sonnet 5 on Tuesday, calling it "the most agentic Sonnet model yet. In its launch post, the company says Sonnet 5's performance is "close to that of Opus 4.8, but at lower prices.