AI & Machine Learning
July 1, 2026Claude Sonnet 5 vs Opus 4.8 vs GPT-5.5: agent cost math
Anthropic launched Claude Sonnet 5 on 30 June 2026 at an introductory 2/10 dollars per million tokens, posting 63.2% on SWE-bench Pro and near-Opus agentic performance at 40-60% of the cost per task. We run the cost math against Opus 4.8 and GPT-5.5, set out a routing framework for when the cheap model wins, and draw the continuity lesson from the eighteen-day Fable and Mythos export-control pause.
Claude Sonnet 5
Claude Opus 4.8
GPT-5.5
Anthropic
AI Agents
Model Selection
Cost Optimization
Microsoft Foundry
Azure
By Technspire Team