I've only just skimmed this blog post but if I'm reading correctly FunctionGemma can work just like what's intended here, a "contextless" tool router.

Going one level up you as a developer have a choice how much context you want to provide to the model. Philipp Schmid wrote a good blog post about this, titling this "context engineering". I like his idea because instead of just blindly throwing stuff into a model's context window and hoping to get good performance, it encourages folks to think more about how what's going into the context in each turn.

https://www.philschmid.de/context-engineering

Similarly I think the blog post you linked has a similar sentiment. There's nuanced approaches that can yield better results if an engineering mindset is applied.