Sonnet 5 Benchmark: How Anthropic's Latest Model Stacks Up Against GPT-5.5 and Gemini
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Lenny's Newsletter
35
Analysis
TLDR
Claire Vo benchmarked Sonnet 5 against GPT-5.5, Gemini 3 Pro, and other models across 64 blind tests using a custom evaluation framework she built live.
Lenny's Newsletter published a hands-on benchmark episode where Claire Vo tested Anthropic's Sonnet 5 against four competing frontier models—including OpenAI's GPT-5.5—using a custom evaluation harness called the How I AI Bench. The test combined human scoring (70%) with LLM-as-judge scoring (30%) across PRD quality, prototype generation, agentic task completion, and agent personality, yielding model-by-task recommendations that surprised the reviewer.
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