Suppose there's a pdf with lots of tables i want to scrape. I mention the pdf url in my message and with gemini's url context tool, i now have access to the pdf

Suppose there's a pdf with lots of tables i want to scrape. I mention the pdf url in my message and with gemini's url context tool, i now have access to the pdf. I can ask gemini to give me the pdf's content as a json and it complies most of the time. But at times, there's an introductory line like "Here's your json:". Those introductory lines interfere with programmatically using the output. They're sometimes there, sometimes not. If I could have structured output at the same time as tool use, I can reliably use what gemini spits out as it'll be in a json, no annoying intro lines.