This seems to be a bug in the documentation, as described in this thread:
Either of these solutions would work, for example:
After taking the iron sword when the iron sword was not handled:
increase the score by 1;
say "Taken.".
(Note the “was” instead of “is”.)
Or:
First carry out taking the iron sword:
if the noun is not handled:
increase the score by 1.
(We use “the noun” in the rule body here to get the actual object which is concerned in the action, otherwise we might run into problems when multiple items of a kind are around, see the thread linked above.)
“For the first time” also works well, but might cause problems in some special situations, as described in chapter 11.4 in the Recipe Book:
we should be careful not to use “for the first time” in scoring situations where it’s possible for the player to try the action but fail. Inform counts even unsuccessful attempts towards the number of times an action is understood to have occurred, so if the player tries to jump and fails, his “for the first time” will be used up and he will never receive the score points.