cd /news/artificial-intelligence/we-removed-over-80-of-claude-code-s-… · home › topics › artificial-intelligence › article
[ARTICLE · art-72924] src=twitter.com ↗ pub= topic=artificial-intelligence verified=true sentiment=↑ positive

"We removed over 80% of Claude Code's system prompt for Opus 5 and Fable 5"

Anthropic removed over 80% of the Claude Code system prompt for its newest models Opus 5 and Fable 5, sharing lessons learned about writing system prompts, skills, and Claude.MDs for them. A user reported that Opus 5 is performing significantly better, particularly for biology tasks, after previously relying on Claude 4.6 and other models.

read1 min views1 publishedJul 25, 2026
"We removed over 80% of Claude Code's system prompt for Opus 5 and Fable 5"
Image: source

We removed ~80% of the Claude Code system prompt for our newest models, this is what we've learned about writing system prompts, skills and Claude.MDs for them.

  • Appreciate it! Opus 5 is performing a lot better Was stuck relying on 4.6 + other models for biology stuff until now
source & further reading
twitter.com — original article
── more in #artificial-intelligence 4 stories · sorted by recency
── more on @anthropic 3 stories trending now
sponsored brought to you by zahid.host 4,200+ EU-deployed projects
reading about agents? ship yours in a single git push.

Run your AI side-project on zahid.host

EU-based hosting, git-push deploys, automatic HTTPS, no cold starts. Free tier with a custom domain — perfect for shipping the agent you just read about.

$git push zahid main
→ Live at https://your-agent.zahid.host ✓
Get free account → Pricing
from €0/mo · no card required
LIVE [news/we-removed-over-80-o…] indexed:0 read:1min 2026-07-25 · —