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?

I have faced similar issue and simple solution was to run RegEx to exclude “【】” and whatever is in there.
I also have tried to give a system prompt to never show those brackets but it wasn’t much reliable