You just installed Cursor, opened a TypeScript file, and asked the agent to fix a bug. Ten seconds later it handed you a type SomeType = any and a @ts-ignore above the line that wouldn't compile. This is the moment most developers discover that AI coding agents are powerful but undisciplined.
The fix isn't a better model. It's rules.
Most AI coding agent best practices boil down to a single idea: tell the agent what good looks like before it starts typing. Cursor lets you define rules files in .cursor/rules/ that load alongside your project context and tell the agent how to behave. Claude Code has its own rules system, Windsurf has a rules directory, Copilot reads .github/copilot-instructions.md. Learn to configure cursor rules properly and your agent starts behaving like a careful senior engineer instead of an eager intern.
What cursor rules files are
Cursor rules are markdown files with a .mdc extension stored in .cursor/rules/ at your project root. Each file is a set of instructions the agent reads before it starts working. When a rule's conditions match the file being edited, the instruction is injected into the model's context window.
