Can a character make an unarmed strike and a claw attack with the same limb during a single turn?

Question

If a Thri-Kreen takes Multi-Weapon Fighting they are allowed to make up to three additional attacks as part of their full-attack action due to having three "off" hands in addition to their one "main" hand. They also racially can make claw attacks as primary or secondary natural weapon attacks, but their hands cannot be occupied at the time. I have seen several discussions about making attacks with manufactured weapons and then dropping them, throwing them as part of your attack, wielding gnomish quick-razors, and even wielding javelins from the Gloves of Endless Javelins as ways of reliably holding weapons until you want your hands free to make natural weapon attacks. However, can the character simply make unarmed strike attacks instead?

For the purpose of this question assume the DM has already ruled characters can wield their unarmed strike as if it were multiple separate weapons and can therefore use it for both mainhand and offhand attacks as part of the same full-attack action. Also, while I am aware that unarmed strikes don't normally need to be made with hands, Multi-Weapon Fighting seems to clearly indicate your extra attacks come from using your extra arms, so I am hoping for a clear ruling one way or another.

TLDR: Is a claw unavailable because a character made an unarmed strike with that arm, or can a classless Thri-Kreen (at ECL 4) take the MWF feat at HD 1 and make a full-attack of 4 unarmed strikes, 4 claw attacks, and one bite?

Answer 1

Consensus

So no rule comes out and says this, to my knowledge, but the universal consensus, in my experience, is No.

We see this reflected in monster stat blocks: you won’t find one where the same limb is shown attacking multiple times in a Full-Attack entry. Rather, the statblock will list several independent options, where the monster uses its weapons in one and doesn’t in another. The marilith is a typical, albeit extreme, example:

Full Attack: Primary longsword […] and 5 longswords […] and tail slap […]; or 6 slams […] and tail slap […]

^{(Monster Manual pg. 44)}

The 6 slams replace the primary longsword and 5 secondary longswords here. We see the tail slap listed in both versions, since the tail isn’t wielding a weapon. But the marilith doesn’t slam with the arm that swung a longsword.

Other monsters are similar. So while this rule isn’t actually found in the text, we see how Wizards of the Coast themselves abided by it.

General Rules

But for the actual rules, all we get is this one paragraph (found in the Monster Manual as well as Rules Compendium):

Some creatures combine attacks with natural and manufactured weapons when they make a full attack. When they do so, the manufactured weapon attack is considered the primary attack unless the creature’s description indicates otherwise and any natural weapons the creature also uses are considered secondary natural attacks. These secondary attacks do not interfere with the primary attack as attacking with an off-hand weapon does, but they take the usual -5 penalty (or -2 with the Multiattack feat) for such attacks, even if the natural weapon used is normally the creature’s primary natural weapon.

^{(Monster Manual pg. 311; Rules Compendium pg. 100)}

It clearly describes mixing manufactured and natural weapons, and the manufactured weapon counting as the “primary” and all others getting relegated to secondary status. But it doesn’t describe the limitations on one’s limbs.

I think this may have been addressed directly in a Rules of the Game article on Wizards’ website, but those are difficult to search now that you have to go through the Wayback Machine. I’ll keep looking for it, but ultimately it only matters so much: the Rules of the Game articles aren’t rules sources, they’re (supposed to be) explanations of the rules. Anything said in there that isn’t said in the actual rules is suspect (and at least a few things are wrong, or at least bad ideas).

Thri-Kreen in particular

It may be relevant to you to point out that the thri-kreen is another typical monster that avoids repeating limbs in its full attack entry:

Full Attack: 4 claws […] and bite […]; or longspear […] and 2 claws […] and bite […]; or javelin […]

^{(Expanded Psionics Handbook pg. 213)}

We see here that when the thri-kreen uses its two-handed longspear, it loses two of its four claw attacks to do it.

Thus, even if one were to try to quibble about primary sources and so on in the general case, for thri-kreen in particular I think it’s a lot harder to argue that you could use claws that have already attacked with a weapon.