According to the Rules of the Game column over at Wizards.com, pretty much anything you could conceivably fit on something will alter its form. So for a tiger, Klaus is pretty much bang-on, aside from the gloves/boots, which shouldn't work. That's assuming you don't wear two items in the same slot.
domino said:
I don't think that they alter shape though. So some stuff, like a vest just wouldn't fit right, and would need to be resized.
All worn items except armour resize to fit the wearer. Weapons and armour resize to fit the user only if the user is capable of wearing armour or wielding a weapon of that type. So a human wearing a breastplate and carrying a longsword, when polymorphed into a troll would be wearing a Large breastplate and carrying a Large longsword. Note that this is not spelled out in the description of the spell, but the Rules of the Game column clarifies this point.
If you don't like the RotG column, then there's a bunch of stuff that's left to discretion and not directly spelled out in the rules. If you follow the column's indications, then it's clear that for everything except armour and weapons, if you can get it on an appropriate body part, it'll size itself to fit. So if a druid wild shapes into an ape, he can wear all his items and use his armour and weapons because his new form is humanoid in shape, despite being an Animal. If he wild shapes into a tiger, he keeps almost everything, but loses the armour and weapons because he can't hold the weapons and the armour is built for a humanoid creature.
And here's the relevent text:
Rules of the Game said:
In general, a change from one form that has a humanoid shape to another form that has a humanoid shape leaves all equipment in place and functioning. The subject's equipment changes to match the assumed form. It becomes the appropriate size for the assumed form and it fits the assumed form. The spellcaster can change minor details in your equipment, such as color, surface texture, and decoration.
When a subject changes from a form with a humanoid shape to a form with a nonhumanoid shape (or vice versa) most of his equipment is subsumed into the new form and becomes nonfunctional. Items the subject could conceivably wear in an assumed form remain functional. For example, most items worn on the body, such as armor, cloaks, boots, and most other items of clothing made for a humanoid body won't fit on a nonhumanoid body. Some items can fit on just about any kind of body. For example, a ring fits just about any form that has digits of some kind (the limit of two rings applies no matter how many hands or similar appendages a creature has). Likewise, a necklace fits on just about any form that has a neck.
Whether you regard this text as "official" or not is up to you, really, but the intention of the column is that it's not supposed to be writing any new rules, only spelling out what's already there. Whether they succeed in this venture is up to debate.
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It's worth noting that magic armour doesn't usually resize to fit the wearer. It only resizes when it already fits the wearer, and the wearer changes form while wearing the armour. But non-magical armour also resizes in that case.
