Simon Willison’s Weblog

llm-fragments-github 0.2. I upgraded my llm-fragments-github plugin to add a new fragment type called issue. It lets you pull the entire content of a GitHub issue thread into your prompt as a concatenated Markdown file.

(If you haven't seen fragments before I introduced them in Long context support in LLM 0.24 using fragments and template plugins.)

I used it just now to have Gemini 2.5 Pro provide feedback and attempt an implementation of a complex issue against my LLM project:

llm install llm-fragments-github
llm -f github:simonw/llm \
  -f issue:simonw/llm/938 \
  -m gemini-2.5-pro-exp-03-25 \
  --system 'muse on this issue, then propose a whole bunch of code to help implement it'

Here I'm loading the FULL content of the simonw/llm repo using that -f github:simonw/llm fragment (documented here), then loading all of the comments from issue 938 where I discuss quite a complex potential refactoring. I ask Gemini 2.5 Pro to "muse on this issue" and come up with some code.

This worked shockingly well. Here's the full response, which highlighted a few things I hadn't considered yet (such as the need to migrate old database records to the new tree hierarchy) and then spat out a whole bunch of code which looks like a solid start to the actual implementation work I need to do.

I ran this against Google's free Gemini 2.5 Preview, but if I'd used the paid model it would have cost me 202,680 input tokens and 10,460 output tokens for a total of 66.36 cents.

As a fun extra, the new issue: feature itself was written almost entirely by OpenAI o3, again using fragments. I ran this:

llm -m openai/o3 \
  -f http://raw.githubusercontent.com/simonw/llm-hacker-news/refs/heads/main/llm_hacker_news.py \
  -f http://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'

Here I'm using the ability to pass a URL to -f and giving it the full source of my llm_hacker_news.py plugin (which shows how a fragment can load data from an API) plus the HTML source of my github-issue-to-markdown tool (which I wrote a few months ago with Claude). I effectively asked o3 to take that HTML/JavaScript tool and port it to Python to work with my fragments plugin mechanism.

o3 provided almost the exact implementation I needed, and even included support for a GITHUB_TOKEN environment variable without me thinking to ask for it. Total cost: 19.928 cents.

On a final note of curiosity I tried running this prompt against Gemma 3 27B QAT running on my Mac via MLX and llm-mlx:

llm install llm-mlx
llm mlx download-model mlx-community/gemma-3-27b-it-qat-4bit

llm -m mlx-community/gemma-3-27b-it-qat-4bit \
  -f http://raw.githubusercontent.com/simonw/llm-hacker-news/refs/heads/main/llm_hacker_news.py \
  -f http://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'

That worked pretty well too. It turns out a 16GB local model file is powerful enough to write me an LLM plugin now!

# 20th April 2025, 2:01 pm / gemini, llm, ai-assisted-programming, generative-ai, o3, ai, llms, plugins, github, mlx, gemma, long-context, local-llms

Gemma 3 QAT Models. Interesting release from Google, as a follow-up to Gemma 3 from last month:

To make Gemma 3 even more accessible, we are announcing new versions optimized with Quantization-Aware Training (QAT) that dramatically reduces memory requirements while maintaining high quality. This enables you to run powerful models like Gemma 3 27B locally on consumer-grade GPUs like the NVIDIA RTX 3090.

I wasn't previously aware of Quantization-Aware Training but it turns out to be quite an established pattern now, supported in both Tensorflow and PyTorch.

Google report model size drops from BF16 to int4 for the following models:

• Gemma 3 27B: 54GB to 14.1GB
• Gemma 3 12B: 24GB to 6.6GB
• Gemma 3 4B: 8GB to 2.6GB
• Gemma 3 1B: 2GB to 0.5GB

They partnered with Ollama, LM Studio, MLX (here's their collection) and llama.cpp for this release - I'd love to see more AI labs following their example.

The Ollama model version picker currently hides them behind "View all" option, so here are the direct links:

• gemma3:1b-it-qat - 1GB
• gemma3:4b-it-qat - 4GB
• gemma3:12b-it-qat - 8.9GB
• gemma3:27b-it-qat - 18GB

I fetched that largest model with:

ollama pull gemma3:27b-it-qat

And now I'm trying it out with llm-ollama:

llm -m gemma3:27b-it-qat "impress me with some physics"

I got a pretty great response!

Update: Having spent a while putting it through its paces via Open WebUI and Tailscale to access my laptop from my phone I think this may be my new favorite general-purpose local model. Ollama appears to use 22GB of RAM while the model is running, which leaves plenty on my 64GB machine for other applications.

I've also tried it via llm-mlx like this (downloading 16GB):

llm install llm-mlx
llm mlx download-model mlx-community/gemma-3-27b-it-qat-4bit
llm chat -m mlx-community/gemma-3-27b-it-qat-4bit

It feels a little faster with MLX and uses 15GB of memory according to Activity Monitor.

# 19th April 2025, 5:20 pm / llm, ai, ollama, llms, gemma, llm-release, google, generative-ai, tailscale, mlx, local-llms

Function calling with Gemma (via) Google's Gemma 3 model (the 27B variant is particularly capable, I've been trying it out via Ollama) supports function calling exclusively through prompt engineering. The official documentation describes two recommended prompts - both of them suggest that the tool definitions are passed in as JSON schema, but the way the model should request tool executions differs.

The first prompt uses Python-style function calling syntax:

You have access to functions. If you decide to invoke any of the function(s), you MUST put it in the format of [func_name1(params_name1=params_value1, params_name2=params_value2...), func_name2(params)]

You SHOULD NOT include any other text in the response if you call a function

(Always love seeing CAPITALS for emphasis in prompts, makes me wonder if they proved to themselves that capitalization makes a difference in this case.)

The second variant uses JSON instead:

You have access to functions. If you decide to invoke any of the function(s), you MUST put it in the format of {"name": function name, "parameters": dictionary of argument name and its value}

You SHOULD NOT include any other text in the response if you call a function

This is a neat illustration of the fact that all of these fancy tool using LLMs are still using effectively the same pattern as was described in the ReAct paper back in November 2022. Here's my implementation of that pattern from March 2023.

# 26th March 2025, 8:23 pm / prompt-engineering, google, generative-ai, llm-tool-use, gemma, ai, llms, local-llms

gemma-2-27b-it-llamafile (via) Justine Tunney shipped llamafile packages of Google's new openly licensed (though definitely not open source) Gemma 2 27b model this morning.

I downloaded the gemma-2-27b-it.Q5_1.llamafile version (20.5GB) to my Mac, ran chmod 755 gemma-2-27b-it.Q5_1.llamafile and then ./gemma-2-27b-it.Q5_1.llamafile and now I'm trying it out through the llama.cpp default web UI in my browser. It works great.

It's a very capable model - currently sitting at position 12 on the LMSYS Arena making it the highest ranked open weights model - one position ahead of Llama-3-70b-Instruct and within striking distance of the GPT-4 class models.

# 2nd July 2024, 10:38 pm / llamafile, google, generative-ai, ai, local-llms, llms, justine-tunney, llama-cpp, gemma, chatbot-arena

PaliGemma model README (via) One of the more over-looked announcements from Google I/O yesterday was PaliGemma, an openly licensed VLM (Vision Language Model) in the Gemma family of models.

The model accepts an image and a text prompt. It outputs text, but that text can include special tokens representing regions on the image. This means it can return both bounding boxes and fuzzier segment outlines of detected objects, behavior that can be triggered using a prompt such as "segment puffins".

From the README:

PaliGemma uses the Gemma tokenizer with 256,000 tokens, but we further extend its vocabulary with 1024 entries that represent coordinates in normalized image-space (<loc0000>...<loc1023>), and another with 128 entries (<seg000>...<seg127>) that are codewords used by a lightweight referring-expression segmentation vector-quantized variational auto-encoder (VQ-VAE) [...]

You can try it out on Hugging Face.

It's a 3B model, making it feasible to run on consumer hardware.

# 15th May 2024, 9:16 pm / google, generative-ai, google-io, ai, local-llms, llms, gemma, vision-llms, image-segmentation

Gemma: Introducing new state-of-the-art open models. Google get in on the openly licensed LLM game: Gemma comes in two sizes, 2B and 7B, trained on 2 trillion and 6 trillion tokens respectively. The terms of use “permit responsible commercial usage”. In the benchmarks it appears to compare favorably to Mistral and Llama 2.

Something that caught my eye in the terms: “Google may update Gemma from time to time, and you must make reasonable efforts to use the latest version of Gemma.”

One of the biggest benefits of running your own model is that it can protect you from model updates that break your carefully tested prompts, so I’m not thrilled by that particular clause.

UPDATE: It turns out that clause isn’t uncommon—the phrase “You shall undertake reasonable efforts to use the latest version of the Model” is present in both the Stable Diffusion and BigScience Open RAIL-M licenses.

# 21st February 2024, 4:22 pm / google, generative-ai, ai, local-llms, llms, gemma