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

12 points · 6 comments · stephenblum

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  1. stephenblum · · focus · HN ↗

    [dead]

  2. sebiandev · · focus · HN ↗
    AI slop warning
    1. stephenblum · · focus · HN ↗
      Yes! You saw it immediately. Article was written by Claude. It has a distinct cadence that matches all the way through writing. It's the same in the CLI claude code
  3. ramon156 · · focus · HN ↗
    [delayed]
    1. stephenblum · · focus · HN ↗
      Yes this is true, you even got the model correct
  4. stratos123 · · focus · HN ↗
    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.
    1. dvt · · focus · HN ↗
      > I have seen people actually not get: that LLMs wrap tool calls in special tokens

      This isn't necessarily true. I'm working on a local harness that doesn't do this and instead coerces everything to YAML (including tool calls) for better bucketing. Some models are indeed trained on the `<|tool_call>...<tool_call|>` token schema (or something similar), but it's vendor-specific and often times inconsistent (so you're constantly fixing calls or going back to the LLM).

      1. stephenblum · · focus · HN ↗
        nice! like HTML tags. I remember seeing this back with meta Llama 2. the <|start_header_id|>assistant<|end_header_id|> style. And [TOOL_CALLS] ... [/TOOL_CALLS] style with Mistral
    2. stephenblum · · focus · HN ↗
      Yes you a are right. The article doesn't mention KV cache. Also, yes the writing is slop, and does not mention the LLM special tokens. Only discusses the use through the OpenAI-style JSON wrapper that allows you to define the schema of a tool call in JSON
  5. KolibriFly · · focus · HN ↗
    An ai wrote a post explaining how to give an ai hands , and half the comments spotted the prose before even reading the code

    peak tech blogging right here

  6. flipflowdev · · focus · HN ↗

    [dead]

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