If you're like me, you want to teach your kids how to resolve their little conflicts by themselves. Tattling is inappropriate attention-seeking behavior, and the tattler is rarely 100% free of responsibility.
Unless someone is bleeding, coughing up a lung or otherwise in danger, the rule in my house is: no tattling. Besides, a parent could spend their entire day mitigating sibling skirmishes! While saving yourself time, you could be teaching them an invaluable life skill.

Here is a great formula for conflict resolution: