Hand-crafted, domain-specific tools massively outperform general purpose ones.

Shell execution and raw DOM access are great for a backstop, but you can go so much further with just a little bit of translation and delegation around the environment.

I think browser automation is probably the most apt scenario. Often a human who understands how a page is meant to be perceived can transform a megabyte of raw web content down to a few hundred bytes of plaintext without any reduction in fidelity. This can be achieved using deterministic code that is guaranteed to provide a perfect transform every time.

The performance difference between raw DOM access and curated plaintext is like a step function. With raw access you get maybe 10-15 steps into a complex workflow before the wheels pop off. With curated access I've seen it go 100+ screens without issues.

Simply managing the token bloat is probably the most important objective here. If that's all you focus on it will probably go really well.