On June 30, 2026, Anthropic officially released Claude Sonnet 5, a new model with sharply improved agentic capabilities. It is positioned as a lower-cost option that delivers performance close to Claude Opus 4.8 , the higher-tier model launched on May 28.
June 30, 2026 · Anthropic
Claude Sonnet 5: Opus-class agents, at the Sonnet price
Anthropic's new model sharpens autonomous tool use, planning and execution — aiming to deliver performance close to the higher-tier Opus 4.8 for a fraction of the cost.
$2 / $10
Intro price per 1M tokens (in/out), through Aug 31, 2026
1M
Token context window, up to 128k output tokens
6
Platforms at launch: claude.ai, Code, API, Bedrock, Vertex AI
Output price per 1M tokens — standard rates
Sonnet 5 lands well below the higher tiers it competes with on capability.
$25
Opus 4.8
high performance
$50
Fable / Mythos 5
frontier
Each block ≈ $5 output / 1M tokens. Sonnet 5 introductory output rate is just $10.
What partners praise
Higher completion on complex tasks
Self-verification cuts follow-ups
Strong on existing (brownfield) code
Token-efficient, fewer turns
Useful in legal, finance, insurance
What critics flag
Opus 4.8 can be cheaper per task
Higher token use may offset savings
More hallucination & flattery reported
Value proposition called unclear
Cybersecurity guardrails
Sonnet 5's cyber capability is intentionally held far below Opus 4.8 and the Mythos tier.
Fable 5 falls back to Opus 4.8 for cyber, biology and chemistry queries. Mythos 5 stays restricted via Project Glasswing — a limited U.S. government and cyber-defender program — with no public release date set while stronger safeguards are built.
Where Sonnet 5 is headed
Multi-step software engineering
→
Agentic coding
→
Data pipelines
→
Legal & finance
→
Computer-use workflows
How far it eases the price–performance trade-off will shape its assessment as AI agents reach practical deployment.
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