Assistant / PDF / output?

Hello - i try to get some answers from a pdf-file and i only want to that he percentage is outputted -

And my phrase in the prompot is something like:
Output only the percentage and nothing else.

Normally this works fine and i only get the output like
42%

But sometimes i get a output like that:
42%【4:0†discount.pdf】

Any easy way to prevent that this additonal stuff with “【】`” is outputted using the assistant?