The question of Hamlet's "antic disposition," whether it is real or feigned and what other characters in the play think of Hamlet's bizarre behaviour is a topic that has inspired much criticism. The first glimpse we gain as to how Claudius interprets Hamlet's behaviour is in Act II scene 2, when Claudius entreats Rosencrantz and Guildenstern to help him in discovering what is the true reason behind Hamlet's "madness" and whether it is anything else apart from his father's death:
Something have you heard
Of Hamlet's transformation: so I call it,
Sith nor th'exterior nor the inward man
Resembles that it was. What should it be
More than his father's death, that thus hath put him
So much from th'understanding of himself,
I cannot deem of...
Now, how we "read" this speech will depend a lot on how you choose to "play" or "read" the character of Claudius in the play at large. He can be shown here to be a genuinely concerned uncle, eager to discover what is going on with his nephew and to try and bring him back to "himself." However, you could also play him as a deceiver, who is manipulating Rosencrantz and Guildernstern into manipulating Hamlet to find out if in some way Hamlet has suspected that Claudius was responsible for King Hamlet's death. Certainly, he does his best to appear as if he were a caring uncle in this speech. Note how he does not use the pejorative term "madness," instead using the euphemistic "transformation" to describe Hamlet's behaviour.
Claudius decides to send for his school friends, Rosencrantz and Guildenstern to "draw him on to pleasures" that is, to cheer him up, and to spy on him.