Language models are best treated like consciousness. Our consciousness does a lot less than people like to attribute to it. It is mostly a function of introspection and making connections, rather than being the part of the brain where higher level reasoning and the functions of the brain that tell your body how to stay alive (like beating your heart).

By allowing a language model to do function calling, you are essentially allowing it to do specialized "subconscious" thought. The language model becomes a natural language interface to the capabilities of its "subconsciousness".

A specific human analogy could be: I tell you to pick up a pen off of the table, and then you do it. Most of your mental activity would be subconscious, orienting your arm and hand properly to pick up the pen, actually grabbing the pen, and picking it up. The linguistic representation of the action would exist in your concious mind (pick up the pen), but not much else.

A language model could very easily call out to a text processing function to correctly do things like count the number of r's in the word strawberry. That is a job that your concious mind can dispatch to your subconciousness.

My consciousness is right a lot more often than a LLM is.

Yet it chose not to read beyond the first sentence :-)