Are you still using the Cursor agent with just a single .cursorrules file in your project root?

Recent community tests show that the latest Cursor agent mode ignores the old root .cursorrules entirely. While compliance with the old format is almost zero, the new format using .mdc files inside the .cursor/rules folder follows rules perfectly. 😄

Instead of stuffing all your rules into one file, you should now break them into multiple mdc files within the folder. Make sure to append .md extension so the rule engine recognizes them properly. YAML metadata at the top of the file is required. You don't have to type it all out—just type c to the /create-rule in the agent chat, and it will generate the mdc file for you based on a prompt. It's surprisingly convenient!

Here is one more pro tip: when the agent mode executes terminal commands, the CURSOR_AGENT environment variable is injected. Sometimes, heavy zsh or bash themes can cause the terminal to slow down or hang. Adding a simple conditional check in your shell config file, as shown below, ensures the agent can execute commands smoothly.

With terminal-based tools like Claude Code and Cursor becoming the norm, 'modularization'—where the agent only reads necessary rules to save tokens—seems to be the key. I highly recommend reviewing your project's rule settings!