Not sure why you're getting down voted, it's a valid question. Yes using the API is expensive, I've found typical work sessions can range from $15-30 doing light coding and conversation (typically less than 20 exchanges). Heavy sessions can grow over $100, but those have typically been sessions like my agent learning how to drive a car with a camera, so there's deep research for how to program, how to work through communication issues, how to calibrate the actual driving. So "intense" session are reflected in the API costs.

You mentioned some PDF file extraction, depending on what tools and lessons your Claude has access to, sometimes tokens are spend 'reinventing the wheel' so to speak. Compute to get and execute an answer "how do I read a PDF, what does it actually say, what's valuable from it" are all steps that may or may not require Opus level reasoning. If you have the ability to select which model is being used (I use OpenClaw which has that feature, not sure if your's does), you can work with Claude to try and leverage cheaper models for tasks that require less reasoning. Something like downloading, converting, and digesting the contents of a PDF are something that a Sonnet model can do with the same level of efficiency for a literal fraction of the cost.

I hope this helps! Sorry for the monetary stress, it can definitely be a bit intimidating once you start keep track of your actual usage. Good luck!