How to use AI coding tools better
An analysis of 100+ Cursor Rules files
AI coding tools just keep getting better and better. If you haven’t watched it already, I’d recommend watching YC’s latest video on vibe coding, which paints a picture of where we are currently at with these tools.
One way that you can control the actions that tools like Cursor take is through an explicit rules file in your codebase. In Cursor, it’s called .cursorrules, but other coding assistants, like continue.dev, support a similar type of file.
These are essentially just system message type prompts that give additional user-defined instructions to the coding agent.
100+ Cursor rules were added to the PromptHub community. I dug through them and found some interesting trends and insights.
Things I found interesting
Below are a few excerpts from some rules that I found interesting. If you want more info, click through the link to see the full prompt
Emphasis on Functional Design
"Use functional and declarative programming patterns; avoid classes. Prefer iteration and modularization over code duplication. Use descriptive variable names with auxiliary verbs (e.g., isLoading, hasError)."
(View full prompt)
Uniform Naming and Style
"Use lowercase with dashes for directories (e.g., components/auth-wizard). Favor named exports for components."
(View full prompt)"Use the function keyword for defining pure functions. Avoid unnecessary curly braces in simple conditionals for cleaner code."
Proactive Error Handling
"Handle errors and edge cases at the beginning of functions; use early returns for error conditions to avoid deeply nested if statements."
(View full prompt)
Automated Testing and QA
"Ensure all tests pass before merging. Conduct thorough code reviews via pull requests; implement comprehensive automated testing (unit, integration, e2e)."
(View full prompt)
Focus on Performance
"Use code-splitting and lazy loading for non-critical resources. Optimize images using modern formats like WebP. Prioritize Core Web Vitals (LCP, CLS, FID)."
(View full prompt)"Utilize Go’s built-in concurrency features when beneficial for API performance."
(View full prompt)
Security Practices
"Validate all inputs. Implement robust authentication and authorization (OAuth 2.0, JWT). Always use HTTPS for external requests."
(View full prompt)"Enforce Content Security Policy (CSP) in manifest.json and use the least privilege principle for requested permissions."
(View full prompt)
Addressing Annoying AI Issues
"Don't apologize for errors—fix them. If code is incomplete, add TODO comments instead."
(View full prompt)
Domain-Specific Recommendations
"Organize Rell code into modules. Follow SQL-like syntax patterns for querying data."
(View full prompt)"Use chrome.alarms instead of setInterval for scheduling tasks."
(View full prompt)
I’ve always found that reading other people’s prompts is the best way to learn, hope this helps!
Prompt template(s) of the week
This week, rather than just a single prompt template, we’re highlighting a group of 200 sales-related prompts that have been added to PromptHub from the Momentum.io team.
Analysing 100+ rules files is a solid approach. The patterns you found (functional design emphasis, naming conventions, early returns) are exactly what people keep reinventing in every tool. Coming to this a bit late but the fragmentation has only gotten worse since you wrote it. There are now seven different file formats for essentially the same thing: .cursorrules, .clinerules, CLAUDE.md, copilot-instructions.md, and more. An open standard called Agent Skills is trying to sort it out. I wrote up the full picture recently if you're curious how the consolidation is going: https://blog.devgenius.io/agent-skills-explained-teaching-your-ai-assistant-new-tricks-c6ee66a632c4