Show HN: My LLM CLI tool can run tools now, from Python code or plugins

I think I want a plugin hook that lets plugins take over the display of content by the tool.

Just filed an issue: https://github.com/simonw/llm/issues/1112

Would love to get your feedback on it, I included a few design options but none of them feel 100% right to me yet.

This one is a ZSH plugin that uses zle to translate your English to shell commands with a keystroke.

https://github.com/day50-dev/Zummoner

It's been life changing for me. Here's one I wrote today:

    $ git find out if abcdefg is a descendent of hijklmnop 

    $ for i in $(seq 1 6); do 
      printf "%${i}sh${i}\n\n-----\n" | tr " " "#"; 
    done | pv -bqL 30 

    $ for i in $(seq 1 6); do 
      printf "(# $i times)\n\n-----\n"
    done | pv (30 bps and quietly)

Yeah, it really does.

There are so many ways things can go wrong once you start plugging tools into an LLM, especially if those tool calls are authenticated and can take actions on your behalf.

The MCP world is speed-running this right now, see the GitHub MCP story from yesterday: https://news.ycombinator.com/item?id=44097390

I stuck a big warning in the documentation and I've been careful not to release any initial tool plugins that can cause any damage - hence my QuickJS sandbox one and SQLite plugin being read-only - but it's a dangerous space to be exploring.

(Super fun and fascinating though.)

I'll switch to o4-mini when I'm writing code, but otherwise 4.1-mini usually does a great job.

Fun example from earlier today:

  llm -f https://raw.githubusercontent.com/BenjaminAster/CSS-Minecraft/refs/heads/main/main.css \
    -s 'explain all the tricks used by this CSS'

The code is clearly written but entirely uncommented: https://github.com/BenjaminAster/CSS-Minecraft/blob/main/mai...

GPT-4.1 mini's explanation is genuinely excellent: https://gist.github.com/simonw/cafd612b3982e3ad463788dd50287... - it correctly identifies "This CSS uses modern CSS features at an expert level to create a 3D interactive voxel-style UI while minimizing or eliminating JavaScript" and explains a bunch of tricks I hadn't figured out.

And it used 3,813 input tokens and 1,291 output tokens - https://www.llm-prices.com/#it=3813&ot=1291&ic=0.4&oc=1.6 - that's 0.3591 cents (around a third of a cent).

We've seen problems in the past where plugins with expensive imports (like torch) slow everything down a lot: https://github.com/simonw/llm/issues/949

I'm interested in tracking down the worst offenders and encouraging them to move to lazy imports instead.

I have an idea to fix that by writing a 'plugins.txt' file somewhere with all of your installed plugins and then re-installing any that go missing - issue for that is here: https://github.com/simonw/llm/issues/575

llm install -U llm

instead of

uv tool upgrade llm

(the latter of which is recommended by simonw in the original post)

The ability to pipe files and other program outputs into an LLM is wildly useful. A few examples:

  llm -f code.py -s 'Add type hints' > code_typed.py
  git diff | llm -s 'write a commit message'
  llm -f https://raw.githubusercontent.com/BenjaminAster/CSS-Minecraft/refs/heads/main/main.css \
    -s 'explain all the tricks used by this CSS'

  llm 'describe this photo' -a path/to/photo.jpg

  llm install llm-cmd
  llm cmd ffmpeg convert video.mov to mp4

I'm getting a whole lot of coding done with LLM now too. Here's how I wrote one of my recent plugins:

  llm -m openai/o3 \
    -f https://raw.githubusercontent.com/simonw/llm-hacker-news/refs/heads/main/llm_hacker_news.py \
    -f https://raw.githubusercontent.com/simonw/tools/refs/heads/main/github-issue-to-markdown.html \
    -s 'Write a new fragments plugin in Python that registers issue:org/repo/123 which fetches that issue
      number from the specified github repo and uses the same markdown logic as the HTML page to turn that into a fragment'

LLM was also used recently in that "How I used o3 to find CVE-2025-37899, a remote zeroday vulnerability in the Linux kernel’s SMB implementation" story - to help automate running 100s of prompts: https://sean.heelan.io/2025/05/22/how-i-used-o3-to-find-cve-...

Most recently I wanted a script that could produce word lists from a dictionary of 180k words given a query, like "is this an animal?" The script breaks the dictionary up into chunks of size N (asking "which of these words is an animal? respond with just the list of words that match, or NONE if none, and nothing else"), makes M parallel "think" queries, and aggregates the results in an output text file.

I had Claude Code do it, and even though I'm _already_ talking to an LLM, it's not a task that I trust an LLM to do without breaking the word list up into much smaller chunks and making loads of requests.

Anthropic's system prompt just for their "web_search" tool is over 6,000 tokens long! https://simonwillison.net/2025/May/25/claude-4-system-prompt...

This post has an unusually large number of code blocks without syntax highlighting since they're copy-pasted outputs from the debug tool which isn't in any formal syntax.