A short story can be anything up to 30,000 words.
Typically most that request a short story request them under 5,000 words if less they are going to publish it.
Short stories can have your ideas implemented if you require them. If you need a thriller you can ask for it to be a thriller, need a certain name in there? Go ahead and ask.
A short story:
Click the image to be taken to a short story that was written within a few hours.