To generate a piece of writing that is under 500 words in English, you could say:

"I need to write an article that is less than 500 words."

Or more specifically:

"Could you help me generate a 500-word or shorter article?"

If you want someone else to do it for you, you might say:

"Can you help me generate a 500-word or shorter article?"

Would you like me to help you with generating such an article on a specific topic?