New Context Engineering Rules for Claude 5 Models
Tariq from Anthropic has published new context engineering rules for Claude 5 models.
These principles have also allowed for a reduction of the system prompt for Claude Code by approximately 80% without measurable degradation in results on their coding benchmark.
tldr:
• CLAUDE.md is only for pitfalls. Remove everything that the model can already understand by studying the repository, and spend tokens on what it can actually stumble over.
• Replace hard prohibitions with style descriptions. Previously, the rule was stated as never write comments. Now it is write code that matches the density of comments and naming in the surrounding code.
• Do not duplicate the same rule in the system prompt and tool description. Keep it only in the tool description.
• Break long skills into several files and upload only what is needed for a specific task.
• The specification does not have to be in Markdown. A test set, HTML layout, or function from another codebase will suffice.
This is more useful than the next ten skills.
Read his material today, and then run /doctor to shorten your own CLAUDE.md and skills.
Why it matters
AnalysisThese new rules can significantly enhance the efficiency of working with AI models, reducing resource expenditure and improving outcomes. They open up new opportunities for developers in utilizing AI technologies.
Discuss in community
Share your questions and insights with developers
Related in Ecosystem
Practical guides, core terminology, and agent skills
Claude Becomes Smarter
Claude becomes smarter, indicating possible improvements in the model's capabilities.
Markdown Format: The Complete Guide for AI Workflows and Automation
A comprehensive hands-on guide to Markdown syntax for AI development: CommonMark standards, heading hierarchy, GFM tables, character escaping, system prompts, and CLAUDE.md guidelines.
Andrej Karpathy Built HackerTube, a YouTube-like Service, in About 2 Hours
Andrej Karpathy used Claude to filter 43 million Hacker News comments into a YouTube-like recommendation service called HackerTube in roughly two hours.
Claude + Excel for Logistics: 10 Ready-to-Use Scenarios for Rate, OTD, and Cost Audits
A practical B2B playbook on integrating Claude with Excel: ready-made system prompts, formulas, and algorithms for analyzing freight variance, OTD, suppliers, and inventory.