I Tested Anthropic's Opus 5.5 Prompting Guide (36 Real Runs)

Get GPUs Runpod: https://get.runpod.io/pe48 Get Hostinger: https://www.hostg.xyz/SHJiu Coupon Code "PROMPT" 10% discount Anthropic published a prompting guide for Claude Opus 5.5. I turned every claim I could check into a with-vs-without test: 36 real Claude Code sessions, same model, same prompts, fresh project copy each run, $12.30 total. What held up: one sentence naming the exact design patterns to avoid took a generated website from 5/5 default "AI look" habits to 0/5 ("avoid a generic AI look" still hit 4/5). Opus 5.5 at medium effort fixed the same bugs as Opus 5 at high with ~42% fewer output tokens and less than half the cost. What didn't show up: the anti-early-stopping paragraph and the pasted-text tags changed nothing in my runs, low effort was not cheaper than medium, and I couldn't confirm the 30% faster-output claim. Small samples, toy project — signals, not benchmarks. Guide: https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-opus-5-5 Setup: claude -p · --setting-sources "" · claude-opus-5-5 / claude-opus-5 · --effort · --append-system-prompt. 🔗 Connect with me: Email → [email protected] Ko-fi → https://ko-fi.com/promptengineer Patreon → https://www.patreon.com/PromptEngineer975 Book a Call → https://calendly.com/prompt-engineer48/call GitHub → https://github.com/PromptEngineer48 Twitter/X → https://twitter.com/prompt48 Website → https://promptengineer48.com/