OPUS 5

Andrej Karpathy gave Opus 5 the first paragraph of the Lord of the Rings, a 1M-token budget (about $10), and asked for a three.js render. Two hours and 5,500 lines of code later, the model had procedurally built a 3D world - and exposed a real weakness in how agents verify their own work.

Running Opus 5 through SlopCodeBench's multi-checkpoint gauntlet reveals that frontier models still degrade codebases over time. 24% strict pass rate, 5x more functions than Opus 4.8, and 93% of code lines trigger slop detectors.

Anthropic removed over 80% of Claude Code's system prompt for Claude 5 models. Here is how the rules changed and what it means for your CLAUDE.md files, skills, and system prompts.

Anthropic released Opus 5 on July 24, 2026 - same price as Opus 4.8, within 0.5% of Fable 5 on CursorBench, and the new #1 on Artificial Analysis. We break down the benchmarks, HN reaction, and what it means for every developer choosing a daily-driver model.

Claude Opus 5 launched July 24, 2026 at $5/$25 per MTok - matching Opus 4.8 pricing while delivering near-Fable 5 intelligence. Full benchmark comparison across 7 evals, pricing breakdown, and decision guide.

Fable 5 lists at $10/$50 per million tokens - twice Opus 4.8. But list price is the wrong number. Here is the cost-per-outcome math that actually decides whether the upgrade pays.

Anthropic launched Opus 5 at $5/$25 and Fable 5 went API-only on July 9. OpenAI shipped GPT-5.6 Sol/Terra/Luna inside Codex and hit 8 million users. Here is the honest July 2026 update on which tool fits which developer.