SCP-XXXX must stay in a bulletproof box.
What are the dimensions? What material? How thick?
Staff should avoid interaction and physical contact with SCP-XXXX, because he is very fragile and could break from a hard force.
If this thing is so fragile, why isn't its box padded? Also, don't refer to the object as 'he', only as 'it'.
hard force..
Vague. Also, one too many periods.
If SCP-XXXX escapes containment just try to tell him a reason why it should get back to his cell, as it is very gullible, like a child.
Your tone really suffers in this sentence. Maybe try something like, 'SCP-XXXX can be easily re-contained due to its gullibility.'
extremely thin body structure.
Vague and non-clinical.
SCP-XXXX .
You just left a spare 'SCP-XXXX' in here.
SCP-XXXX has no special abilities although he could punch or kick.
Why is this sentence here? We already know that it's animate, so there's no real need to specify its ability to punch or kick. The tone also is pretty bad here.
Angering it could result in any of these, he would beat you to death if you anger him enough although he would break his fist.
'SCP-XXXX resorts to violence when angered, often resulting in the breaking of its limbs.'
If speaking to SCP-XXXX, staff should not refer to its visible internal organs, because he will get offended and throw a "tantrum".
'Staff should refrain from mentioning SCP-XXXX's internal organs when communicating with it, as doing so angers SCP-XXXX.'
SCP-XXXX was found in a playground in china, caught trying to play with the other kids, upset because the kids are terrified of it.
Vague and non-clinical. If this is all the backstory you're going to give, you might as well leave it out.
we
Don't. Don't refer to the Foundation as 'we' when trying to be clinical.
When he was finally caught and contained we had problems with the way he acted, some of the MTF guards were beaten and SCP-XXXX attempted to run many times.
This sentence is all over the place grammar-wise. Additionally, how does a kid beat up an MTF? It just doesn't make sense.
SCP-XXXX has organs visible threw its glass skin.
This should really be mentioned at the beginning of the article.
Addendum: SCP-XXXX appears to have many cracks.
Again, should be stated at the beginning of the description.
Incident XXXX-A: SCP-XXXX breaks his fingers after attempting to harm a class-d.
This is short and pointless.