
Claude Code Models and Effort Levels: Explained Simply
Model selection and effort level solve different problems. The model controls Claude’s underlying capability; the effort level controls how much work Claude does before responding.

Model selection and effort level solve different problems. The model controls Claude’s underlying capability; the effort level controls how much work Claude does before responding.

Claude Fable 5 and Claude Mythos 5 were temporarily suspended after the US government applied export controls on June 12, requiring Anthropic to restrict access to foreign nationals. Because Anthropic says it had no reliable way to verify nationality in real time, it suspended both models for all users. Those controls were lifted on June 30, and Fable 5 was restored globally starting July 1 across Claude Platform, Claude.ai, Claude Code, and Claude Cowork.

Anthropic released Claude Opus 4.8 on May 28, 2026 — a sharper, more honest upgrade to Opus 4.7 at the same price. Here's a clear breakdown of every new feature, capability, and how it compares to the previous model.

Claude Sub-Agents — The npm for AI developers! (sub-agents CLI)