I benchmarked the NEW Sonnet 5. The results shocked me.
I’ve been testing every major frontier model release since the start of the year, and when Anthropic dropped Sonnet 5, I wanted more than a vibe check. I got tired of one-off tests I couldn’t repeat or compare over time, so I built something better: the How I AI Bench, a repeatable eval harness I constructed live using Claude Code while recording this episode. I ran Sonnet 5 blind against four other frontier models (Sonnet 4.6, Opus 4.8, GPT-5.5, and Gemini 3 Pro) across PRD quality, prototype generation, agentic task completion, and agent personality. The results were not what I expected. *What you’ll learn:* 1. What Anthropic claims Sonnet 5 improves over Sonnet 4.6, and where the benchmark data actually backs that up 2. How I built the How I AI Bench in under 45 minutes using Claude Code, starting from my own stored session history 3. Why I combined human vibe scoring (70%) with LLM as judge scoring (30%) instead of trusting either alone 4. How to set up a local HTML scoring page so you can rate AI outputs on gut feel and export those scores as JSON 5. Which model I recommend for PRDs, which for complex prototypes, and which for chatting with an agent daily *Brought to you by:* Runway—The creative AI platform for images, video and more: https://runwayml.com/howIAI Hyperagent—Deploy fleets of agents that handle real work: https://www.hyperagent.com/howiai *In this episode, we cover:* (00:00) Sonnet 5 is out (01:55) What Anthropic claims (04:02) Why I’m done with one-off vibe checks (05:05) Building the How I AI Bench live with Claude Code (07:42) The scoring system (10:43) Agent voice eval (11:57) Quick recap (13:58) Results: The How I AI index leaderboard (21:21) What I’m improving for the next run (22:16) Generating a Claire-weighted index (23:53) Model-by-task recommendations *Blog and detailed workflow walkthroughs from this episode:* Building a Custom Benchmark for Sonnet 5, and Why the Results Surprised Me: https://www.chatprd.ai/how-i-ai/sonnet-5-review-and-custom-benchmark ↳ How to Conduct a Blind ‘Vibe Check’ to Evaluate AI Model Quality: https://www.chatprd.ai/how-i-ai/workflows/how-to-conduct-a-blind-vibe-check-to-evaluate-ai-model-quality ↳ How to Build a Custom AI Model Benchmark Using Claude Code: https://www.chatprd.ai/how-i-ai/workflows/how-to-build-a-custom-ai-model-benchmark-using-claude-code ↳ How to Create a Weighted Index for AI Model Benchmark Results: https://www.chatprd.ai/how-i-ai/workflows/how-to-create-a-weighted-index-for-ai-model-benchmark-results *Tools referenced:* • Claude Sonnet 5: https://www.anthropic.com/news/claude-sonnet-5 • Claude Opus 4.8: https://www.anthropic.com/news/claude-opus-4-8 • GPT-5.5 (OpenAI): https://openai.com/index/introducing-gpt-5-5/ • Gemini 3 Pro (Google DeepMind): https://deepmind.google/models/gemini/pro/ • Cursor: https://www.cursor.com/ *Other references:* • SWE-bench Pro (agentic coding benchmark referenced): https://www.swebench.com/ *Where to find Claire Vo:* ChatPRD: https://www.chatprd.ai/ Website: https://clairevo.com/ LinkedIn: https://www.linkedin.com/in/clairevo/ X: https://x.com/clairevo _Production and marketing by https://penname.co/._ _For inquiries about sponsoring the podcast, email jordan@penname.co._
