5 Cursor rule mistakes that make the AI ignore you

Your .mdc files might look fine. Cursor won't tell you they're broken.

Cursor reads your .cursor/rules/ directory to understand how you want code written. But it doesn't validate your rules. If something is wrong, you won't see an error. You'll just notice Cursor "ignoring" your instructions and wonder why.

These are the five most common mistakes. All of them are found in real, public repositories. All of them are silent.

#1. The rule that never loads

---
description: TypeScript naming conventions
alwaysApply: false
---
Use camelCase for variables and functions.
Use PascalCase for classes and interfaces.
Never abbreviate variable names.

What's happening: When alwaysApply is false and there are no globs, the rule only activates if you reference it by name in chat. Most people never do. The rule exists in your directory, consumes zero tokens, and does nothing.

This is the single most common Cursor rule mistake. Over 5,000 public repositories on GitHub have rules configured this way.

The fix

Either set alwaysApply: true if you want it active on every request, or add globs to scope it to specific files:

---
description: TypeScript naming conventions
globs:
  - "**/*.ts"
  - "**/*.tsx"
---

#2. The contradiction

Always use semicolons at the
end of statements.
Use double quotes for strings.

Omit semicolons at the end
of statements.
Use single quotes for strings.

What's happening: Cursor receives both rules in its context window. They say opposite things. Cursor picks one (unpredictably) and follows it. This is especially common when rules are copied from different sources or written by different team members.

Full guide: How to fix Cursor rule conflicts covers how to find, diagnose, and resolve every type of rule contradiction.

#3. The token hog

---
description: General coding standards
alwaysApply: true
---
Write clean code.
Follow best practices.
Use proper naming conventions.
Handle errors properly.

What's happening: Every rule with alwaysApply: true gets loaded into the context window on every request. Vague instructions like "write clean code" don't change what the model does. They just consume tokens that could be used for actual code context. The model already follows best practices. Telling it to do so is like telling a chef to "cook good food."

The quick fix: Replace "write clean code" with "max 20 lines per function, extract helpers over nesting." Replace "handle errors properly" with "wrap route handlers in try-catch, return {error, code} on failure."

Full guide: Cursor token budget: how many rules is too many? covers how to measure your total token usage and cut waste.

#4. The Windows developer

---
description: React component conventions
globs:
  - "src\components\*.tsx"
  - "src\pages\*.tsx"
alwaysApply: false
---
Use functional components with hooks.
Never use class components.

What's happening: Glob patterns use forward slashes on all platforms. Backslashes are escape characters in most glob implementations. src\components\*.tsx doesn't match src/components/Button.tsx. The rule never loads for the files you intended.

This one is invisible because the rule is valid YAML and has correct frontmatter structure. Everything looks right until you realize the globs don't match anything.

The fix

globs:
  - "src/components/**/*.tsx"
  - "src/pages/**/*.tsx"

Always use forward slashes in globs, even on Windows.

#5. The YAML crime scene

---
description: 	Rules for my project
globs: "*.ts, *.tsx, *.js"
alwaysApply: "true"
priority: high
---
Follow best practices.
Write clean code.

What's happening: Six issues in eight lines. alwaysApply: "true" (with quotes) is a string, not a boolean. Cursor may not interpret it correctly. The priority key doesn't exist in the .mdc spec and gets silently ignored. Comma-separated globs may not parse as you expect. Tabs in YAML can cause parsing errors in some environments. And both instructions are too vague to change model behavior.

Each of these issues is minor on its own. Together, they create a rule that might partially work, partially fail, and is impossible to debug without a linter.

The fix

---
description: TypeScript and JavaScript standards
globs:
  - "**/*.ts"
  - "**/*.tsx"
  - "**/*.js"
---
Use const for all variables that aren't reassigned.
Wrap async operations in try-catch blocks.
Return early from functions instead of nesting if/else.

How to check your own rules

All five of these mistakes are caught automatically. Run this from your project root:

npx cursor-doctor lint

It scans every .mdc file, checks for 100+ issues including all the patterns above, and tells you exactly what's wrong and how to fix it. No install, no config, zero dependencies.

For a quick health grade:

npx cursor-doctor scan

Related guides

• How to lint your Cursor rules
• How to write Cursor rules that actually work
• How to fix Cursor rule conflicts
• Cursor token budget: how many rules is too many?

npx cursor-doctor lint