How AI tool calling works (40 lines of vanilla JavaScript)

sebiandev

AI slop warning

ramon156

Thank you Claude, very cool!

stratos123

The writing is slop. It doesn't mention a detail I have seen people actually not get: that LLMs wrap tool calls in special tokens, so they are "out of band" and can't be mistaken with normal output. It also spends an entire section trying to convey that large tools waste tokens: A read_file that returns an 8k-token source file on turn 2 of a ten-turn agent gets resent on the eight requests that follow: 8 × 8k = +64k input tokens, $0.32, from one tool result. but surely that's wrong - it's part of the same conversation, it only gets processed once and then cached. Otherwise doing long conversations would always cost an amount quadratic with length.