A toy should not make light of sin, make evil seem good or incite sin.
“Fools mock at sin, But among the upright there is good will.” Proverbs 14:9 (NASB)
“It would be better for him if a millstone were hung around his neck and he were thrown into the sea, than that he would cause one of these little ones to stumble.” Luke 17:2 (NASB)
I would never let my daughter leave the house dressed like modern Tinker Bell imagery, so she will not be playing with toys containing such imagery. Barbie and Ken are sure examples of making light of sin, Mattel has created a pair in a sinful relationship focusing on only the sensual. Then we have an abundance of occult toys, it would be impossible to play with a Ouija Board without sinning and giving one is a sin in itself.
A toy should have some teaching value.
“Train up a child in the way he should go, Even when he is old he will not depart from it.” Proverbs 22:6 (NASB)
There is nothing inherently evil with a toy with no teaching value; however such toys seem to be poor stewardship of time. Toys that teach are just as much fun for a child. That being said, more toys then you think have teaching value. A doll can teach a girl how to be a mother. A ball teaches coordination and physical education.
Toys should not be excessive.
“A Psalm of David. The earth is the LORD’S, and all it contains, The world, and those who dwell in it.” Psalm 24:1 (NASB)
We should be teaching children to store up their treasures in heaven, not here on earth (Matthew 6:19-21). We must be careful to keep Christ at the center of our lives and our children’s lives. Lavishing a child in excess can make the child more central than Christ in the parent’s lives and can make the child think they are the central focus of life. Being a good steward will often mean spending on kingdom work rather than yet another toy for your child.
Cheap toys frustrate children, break and wind up in the trash: a poor show of stewardship. Look for fewer toys of quality construction. Look for toys that encourage imagination and creativity. Such toys can help fight excess. A set of plain wood blocks can be made into just about anything with some creativity. Compare that to these specialized building kits, you need one box to build a boat and you need to buy another box to build a car, etc, etc. The plain blocks fight excess because they are so versatile. They are the boat, the car, and everything else you can dream up.