Response token count much higher than expected

Hello. I am running into issue with max response size. The agent is trying to extract data from text, and return results as array of objects in structured output. Each object has exact same structure and contains of 8 keys of short Stings. I am using Gemini 2.5 pro.

  • with default 8k max response token count I get only up to 26 objects in array, rest is ignored
  • with max 64k I get around 120 objects maximum in my array

this has been consistent and and the amount of data is much lower then expected for these token numbers. I can see in the logs tokens are being spend and billed.

I would like to now what is happening and what can I do

Thanks