How Cursor, Claude Code, and Codex actually load your project rules (and why yours get ignored)
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Learn how AI coding tools like Cursor, Claude Code, and Codex load project rules and why yours may get ignored
Action Steps
- Read the documentation for your AI coding tool to understand how it consumes project rules
- Check the file format and naming conventions for your tool, such as .cursor/rules or CLAUDE.md
- Test your project rules file with a simple example to ensure it's being loaded correctly
- Compare the behavior of different AI coding tools to identify potential inconsistencies
- Apply best practices for writing project rules files, such as using clear and concise language, to improve readability and adoption
Who Needs to Know This
Developers and AI engineers working with AI coding tools can benefit from understanding how project rules are loaded and applied, to improve collaboration and efficiency
Key Insight
💡 AI coding tools consume project rules files in unique ways, and understanding these differences is key to effective collaboration and automation
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🤖 Did you know AI coding tools load project rules differently? Learn how to write effective rules files for Cursor, Claude Code, and Codex
Key Takeaways
Learn how AI coding tools like Cursor, Claude Code, and Codex load project rules and why yours may get ignored
Full Article
Every AI coding tool now has a "project rules" file. Cursor has .cursor/rules , Claude Code has CLAUDE.md , OpenAI Codex has AGENTS.md . Teams write them once, watch the agent ignore half of it, and conclude the feature is broken. Most of the time the feature isn't broken. The rules file is written for a human reader, and each tool consumes it differently. Here's how the three tools actually load rules as of mid-2026, and the writing habits that tran
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