See also long tanru for another viewpoint.
It sounds tempting, if a single brivla or a gismu seems too vague, to make a tanru; and if the tanru is still too vague, to make a more complex tanru. This can often be communicatively effective.
But the more components in the tanru, the more semantic ambiguities there are, because each tanru joint introduces one or more ambiguous meanings, and the ambiguities, quite literally, multiply.
On the other hand, a tanru with 1000 gismu should be pretty specific.
The final defense is to make a new lujvo and nail down its meaning.
(This is if you think one can only communicate using semantically
exact utterances. Whereas I insist that most human usage differs
from this, in that there is much assumed meaning taking place, and
then each utterance modifies the context in a minimalistic way. In
essence, the course of the ball both teams are playing with, gets
nudged this way or that; what utterances mark is the change in
direction. Therefore tanru are perfectly adequate for everything
except the formal discourse of philosophers and scientists... but
don't let me keep you from taking twenty five Lojban words to
order a cup of coffee!)
In actual communication, which almost always occurs between who share a universe of discourse, there are but so many ideas that can be comprehended; the universe of discourse is of finite extent in a hypothetical space of concepts. So while a long tanru might select a huge number of concepts, all the tanru really needs to do is "space apart" the [members of the set of] possible interpretations such that only one is within the universe of discourse (the others are meaningless jibberish or undiscovered concepts), and also within the context of the discussion! --xod