Show HN: Needle2: 14MB agentic LLM for phones, wearables, smart home and robots

cactuscompute.com

193 points by HenryNdubuaku 9 hours ago

Hey HN,

Henry from Cactus here!

We previously released Cactus Needle, a 14MB agentic LLM for tool call, device use, and structured extraction for phones, wearables, smart homes, small robots and microcontrollers. We got really great feedback here, and have now incorporated the suggestions to release Needle 2.

The whole model is a single 14MB binary that runs a full session in 28MB of RAM; 45m parameters at 2bit compression. Needle hits 500 tokens/sec decode speed on a Raspberry Pi 5, sits between 400-1,500 tokens/sec on VR devices like Meta Quest 3S and Apple Vision Pro, and ranges 300-700 on sub-$200 phones such as the Samsung A-Series.

On the tool call and mobile device use benchmarks, Needle 2 trades wins with closest small models like LFM2.5 230M and Apple Foundation Model, at 5x to 70x smaller, both at f16 vs Needle 2 at 2bit. Needle is based on Simple Attention Networks from our paper (https://arxiv.org/abs/2607.18363).

Edge AI has lately meant Macs and PCs, but that is just 1.5 billion of over 21 billion connected IoT devices in the world today, and in emerging markets most phones ship under $200, no NPU, cheap GPUs. These include budget phones, Raspberry Pis, microcontrollers, wearables, small robots like Reachy Mini, and connected home devices.

A conventional transformer of Needle's width and depth spends 164 MFLOPs per token, and even one squeezed down to Needle's parameter count spends 87, Needle spends 70. Even on a high-end phone, an always-on assistant lives inside a power budget; every MFLOP is milliwatt-hours, and Needle spends 7x to 85x fewer of them per token than the smallest performant LLMs. More about the architecture in the link.

When we structure intelligence for consumer devices as functions with typed parameters, the only hard part is mapping a messy sentence onto them; which function, with which values. Our research found that when framed that way, the problem needs no world knowledge and no open-ended prose, which is why 45M parameters suffice.

Needle 2 expands to structured extraction where the schema can be passed in-place of tools and the model returns structured output. You can use Needle as a text-classification model with an enum field, as a summarization model by providing a schema that extracts key fields, everything but free-range decode.

Every product has its own tool vocabulary and fine-tuning needle helps it achieve frontier-level performance on custom tasks, so using the python package (https://github.com/cactus-compute/needle), Needle can be fine-tuned Needle on a Mac/PC in minutes to a few hours, with automated data-generation pipeline, just pass a couple samples.

Nonetheless, every response carries a learned confidence score based our Cactus Hybrid technique. If above your threshold, act, below it, escalate to the cloud or bigger model. Combining Needle 2 with a private DeepSeek-v4-Flash deployment works particularly well for enterprise-level tasks at barely any cost, we can help with this setup.

We have put a lot of thoughts into Needle 2 but might still be missing quite a lot, please use the playground in the provided link to test Needle and share your thoughts, always appreciated!

nater5000 4 hours ago

This is cool. I definitely think the "micro" sized LLM space is underappreciated, so it's always good to see work like this. I foresee a paradigm in some contexts where you have a hierarchy of LLMs, with more competent models actively training smaller models to solve specific tasks very efficiently, and something like this could be the smallest layer in that stack.

With that being said, the web demo is not particularly impressive. It really doesn't like anything I throw at it. I'm fine with accepting that fine-tuning is the solution to this, but I wonder if there's anything to gain from a bigger model? I know it's completely counter to the whole point of this, but a 14MB binary using 28MB of RAM seems unnecessarily small and pretty arbitrary.

Like, what does a 28MB binary get you? Or a 140MB binary? Or a 1.4MB binary? I'm guessing the choice of 14MB came from minimizing the size as much as possible while meeting certain requirements/performance expectations, but even a Pi 5 has plenty more room to spare. Curious if there's a good explanation for this (which I may have missed in my skim of the post).

  • HenryNdubuaku 4 hours ago

    So, its not a general language model, focused on tool call strictly for tiny edge-devices. There are solutions everywhere for high-capacity devices, Needle is for sub-$200 devices.

    • fwipsy 2 hours ago

      14mb? More like sub-$20 devices.

      • TomatoCo 2 hours ago

        Most pi pico's come with 16mb of flash. I wonder what kind of performance that can eek out.

        • SequoiaHope 43 minutes ago

          Well running from QSPI flash (even the internal memory versions use SPI internally) so any inference would be very slow streaming from that compared to RAM. The featured article says: “With a peak session RAM around 28MB, Needle runs on newer microcontrollers like ESP32-S3.” So I don’t see this doing anything useful on a Pico. The Pico 2 (RP2350) for example has 520k of RAM.

dbeardsl 1 hour ago

My first query:

> Make it a little warmer in here.

The reply:

> "name": "set_thermostat", > "arguments": { > "temperature": 65, > "mode": "cool", > ... > "reasoning": "'warmer' implies need for cooling; set_thermostat with temperature 65 (typical warmth) and mode 'cool'.",

Maybe I'm doing it wrong?

  • dannyw 1 hour ago

    It's not a conversational model. It's meant as a local tool calling model.

    • derangedHorse 1 hour ago

      Yes, I think OP understands that. What he and many others in this thread are trying to understand is what makes this model useful.

Tiberium 5 hours ago

Funny result from the web demo. I'm well aware that it's an extremely small and, well, stupid, model, but even so:

Query: HN

Result:

{ "function_calls": [ { "name": "lock_door", "arguments": { "door": "front door" } } ], "reasoning": "User wants to lock the door. No specific door mentioned, so use 'front door' as default.", "confidence": 0 }

I'd expect it to at least ignore (call no tools) for the queries that it doesn't understand. And it seems like it does do that, just not consistently.

  • jszymborski 5 hours ago

    no, this is the appropriate response to hearing the words "HN" :P

  • Schiendelman 5 hours ago

    Was that the first message you sent it?

  • yoavm 5 hours ago

    The website says the model is for "tool calling, device use, and structured extraction". Your example just doesn't seem to be very relevant. FWIW, it did a pretty good job for tool calling when I tried it, and I think it could be pretty nice to have this running on locally and integrate with Home Assistant.

    • evmaki 5 hours ago

      False positives are definitely relevant and worth measuring - natural language interfaces always have a discoverability problem, i.e., users not knowing what actions the system does and does not support. If the frontend of that system lacks the ability to reject unsupported commands, weird stuff happens.

      Nonetheless, this is very cool work! If I can offer a small suggestion to the team at Cactus, it would be to evaluate your releases on some usability criteria (including false positives). Any serious integrator or adopter of these models would want to have that information available.

      • jdknezek 5 hours ago

        > "confidence": 0

        OP and the linked page talk about the confidence score and using it as an action threshold, so it looks like an appropriate total response to me.

        • evmaki 4 hours ago

          Right, but that's not the same thing as reporting a benchmark across a test set. It doesn't help me determine how well the model does across a decently-large sample size of commands. It doesn't tell me with what reliability the confidence will be below a given threshold when it should be, above that threshold when it should be, etc.

    • curious_cat_163 1 hour ago

      I think the test above is about tool calling... That's how I read it. The issue here is known as "out of distribution detection" in the old-timey classification world.

      I am not sure how a micro model will fundamentally solve it. Would love to understand what dannyw and team did there?

      • derangedHorse 1 hour ago

        How did you draw an association between dannyw and Cactus? There are no 'Danny's on the list of GH contributors nor is there one named in the paper. Just curious.

  • petu 5 hours ago

    "confidence": 0, so I guess you could threshold it

  • hmokiguess 5 hours ago

    yeah I got the same, almost like its biased heavily towards that as the 0 ranking -- my prompt was just the word 'potato'

  • HenryNdubuaku 4 hours ago

    This is exactly why the confidence feature was introduced, the model knows when its wrong, we could hide that part and return a placeholder "sorry I only do function calls", would that be better or you prefer to see everything?

  • plingbang 3 hours ago

    I've got an identical output with the prompt "do not lock the door".

pylotlight 37 minutes ago

What about use case for replacing regex? I.e "random formatted title.extension" - extract the title or some tag or something for more dynamic string manipulation for pulling structured data out of strings efficiently and more simply than regex provides?

profsummergig 4 hours ago

Could someone please share how such open source micro-LLMs might have been created?

Do the creators take something like DeepSeek, and then delete most of the neurons to whittle down the size?

  • HenryNdubuaku 4 hours ago

    Technically, you could do that, but we trained this one from the ground up!

    • profsummergig 2 hours ago

      That sounds like an enormously expensive exercise.

      • ronsor 2 hours ago

        At <50M parameters, training costs are completely trivial. You'll spend a lot more on your rent this month.

      • salamo 2 hours ago

        As someone who's done something similar (https://blog.lukesalamone.com/posts/creating-tiny-semantic-s...) the expensive part wasn't the training itself but the data curation and evaluation post-training. For this, getting a reasonable distribution of tool calls when the tool call can be anything isn't easy.

        Once you have that, the model is small enough batch sizes are probably enormous and training can probably be done on a consumer-grade GPU in a week or less. Or even faster on a bigger GPU.

      • genxy 1 hour ago

        You can train a model of this size on your laptop in a day.

      • kadoban 1 hour ago

        Training scales pretty badly, so smaller models like this are really not that bad in terms of cost.

  • hgoel 3 hours ago

    Another option for something this small and narrowly specialized could be to get traditional LLMs to synthesize the training data. Model collapse is probably less of an issue at this size relative to terabyte sized models.

  • anigbrowl 1 hour ago

    There's a Manning book on creating your own LLM from scratch which answers your question exactly. There's another book from the same publisher specifically about small language models for specialty purposes.

arthuqa 5 hours ago

That's really cool - I was already thinking of compressing `functiongemma-270m-it` down to 1-2 bits so it would work flawlessly in the browser. Your `Fine-tuning` feature is even much more convenient.

hathym 4 hours ago

I tested with

  import needle

  @needle.tool
  def add(a: int, b: int):
      "Add two numbers."
      return a + b

  agent = needle.Needle(tools=[add])
  print(agent.run("calculate 1 + 1?")["reasoning"])

python main.py No calculator or math tool available.

conclusion: completly useless

  • HenryNdubuaku 4 hours ago

    Try the following tool description: "Calculate the sum of two numbers. Use for any arithmetic or math question." instead of "Add two numbers." Let me know how it goes, thanks!

    • HenryNdubuaku 4 hours ago

      It does better with clearer tool description, but we are taking note of these complaints for future improvements.

    • hathym 4 hours ago

      works better that way, thanks :)

      • HenryNdubuaku 4 hours ago

        Thanks, we shall improve this for the next release.

      • hathym 4 hours ago

        but still struggle when changing the quesion:

          import needle
        
          @needle.tool
          def add(a: int, b: int):
              "Calculate the sum of two numbers. Use for any arithmetic or math question."
              return a + b
        
          agent = needle.Needle(tools=[add])
          print(agent.run("what is 5 + 7?")["reasoning"])
        
        

        >> No calculator or math tool available. Cannot compute numbers.

        • HenryNdubuaku 4 hours ago

          Ah, another failure point on our end! So a simple "5 + 7" and "add 5 and 7" works. But to handle ambiguity, the python package ships pipelines to synthesize augmentations and fine-tune on your samples for robustness. Just run "needle playground" and use the UI. Apologies.

redrix 4 hours ago

This is cool!

While most of the industry focuses on the frontier of “intelligence” (function), a release like this represents the frontier of the other end of the spectrum (form).

Both are important if we ever want to see “Opus-level” capability running locally on commodity machines in the future.

  • dalemhurley 3 hours ago

    agreed, this is where we have the biggest opportunity for innovation.

dangoodmanUT 2 hours ago

> turn on the tv

{ "function_calls": [ { "name": "lock_door", "arguments": { "door": "tv" } } ], "confidence": 0.0158 }

Very interesting, seems confidence is 0 when tool calls are right?

  • pylotlight 40 minutes ago

    You may want to reword that.. what do you think 0 confidence means... ?

tolugenius 5 hours ago

This is really cool, I'm curious how much knowledge can their be in smaller models? It seems the current trade off is you need sizeably larger models for more performance but I'm curious if in your work how far this is true, as edge ai is really what needs to get better before physical ai can take off (my two cents).

  • msdz 5 hours ago

    I imagine at such a low parameter count, there would be little to no world knowledge whatsoever, and the entire focus is on getting the structure of tool calling etc. right…?

    But yeah, in terms of “physical” AI, robotics definitely comes to mind for me as well, where tool calls/structured “device” use in a “realtime”/edge application are highly beneficial (if you wanted to go with LLMs), but beefy hardware can’t be easily used.

    • rshemet 6 minutes ago

      Roman from Cactus here -

      yes you're right, there's only so much a 14MB model can do.

      Needle excels at in-conext inference, with tightly defined environments. In our experience:

      accurate descriptions + narrow tool scope = success

hgoel 4 hours ago

Makes me think of the demo from some time ago where someone got a ~29M parameter model running on an esp32. I wonder what kind of throughput this could get if a handful of esp32s were strung together...

Edit: I have a pile of d1 minis, but not much time.

  • forsalebypwner 4 hours ago

    They mention that this specific model is able to run on an ESP32-S3, or an ESP32-P4 which has 32MB of PSRAM. I'm trying to figure out how to do this now.

  • HenryNdubuaku 4 hours ago

    That demo was Needle 1 indeed and we are creating the guide for ESP32 now as we speak.

mmastrac 2 hours ago

Congrats on this release. The WASM implementation is really cool. This is a surprisingly good fit for a lot of cases, and I totally want to try turning this into a helper assistant for an application.

Please, though, take a pass at humanizing the text on the page. It's Clauded up all over and makes it hard to read.

skavi 4 hours ago

I wonder if there's any way to get this to plan out a dag of tool calls? i.e. use the results from earlier calls as the parameters to later ones? I tried introducing a stack based system, but gave up pretty quickly.

  • HenryNdubuaku 4 hours ago

    Yes, though for better results in production, after creating your tool json, use the provided data synthesis and fine-tuning pipeline. It tunes on on your mac.

minimaltom 5 hours ago

Was really cool to see yous use Engrams to cut down compute!

Given its basically an O(1) lookup with disk space being the main constraint, I was curious if you've tried ablating engram layers and sizes across your setup?

Also, why mHC over attention residuals?

  • HenryNdubuaku 5 hours ago

    Yes, we ablated Engrams rigorously and found that it returned world knowledge like FFN without without compute expenditure.

    • minimaltom 4 hours ago

      What about mHC? I'm surprised it helped with such a small compute budget.

dofm 5 hours ago

Naïve and clumsy question: how would you pair this with speech-text-speech stuff, wake words etc.? Are there good examples of this for a Pi 5?

The demo is super — I'm just having trouble seeing the whole picture for e.g. a screenless device.

ETA: pun not intended

  • HenryNdubuaku 5 hours ago

    Users often stack a transcription model on top to get the voice prompt, then decode to actions. Think of Alexa and Siri.

    • dofm 4 hours ago

      Thank you.

  • nater5000 5 hours ago

    The best entrypoint is Home Assistant: https://www.home-assistant.io/

    That will get you a lot further than what you're asking, but if you dig a bit through Home Assistant features, resources, etc., you may find the current "best" answers to your questions.

    If you want a quick answer: Whisper is a good open-source speech-to-text model which comes in a variety of sizes (https://huggingface.co/openai/whisper-tiny). You can definitely get something like this running on a Pi 5. There are plenty of other STT models out there, some of which are built specifically for this context (again, see the Home Assistant stuff), but Whisper comes up a lot as a good default choice.

    So with something like Whisper, you could just have a simple script which is constantly listening to a rolling window of audio and transcribing it. When the transcription includes a key phrase, you can pass the rest of the transcription to Needle2 (or anything else for that matter). From there, you take the results and execute the necessary tool calls.

    There's a bit more to all of this to make it work smoothly, but fundamentally this is all there is to it. All this would work very fast on a Pi 5 (although I wouldn't expect the results to be particularly good without some serious hand-crafted logic, fine-tuning, etc.). If you want to mess around this stuff, handing all of this to Claude, Codex, etc., can get you something spun up and functional very quickly.

    • dofm 4 hours ago

      This is a very responsive answer, thank you so much. (I'd assumed maybe Whisper but the wake word "loop" detail there is illuminating.)

sroussey 3 hours ago

Looking forward to npm version of needle-rs supporting v2. I added needle support for tool use in my side project.

  • HenryNdubuaku 3 hours ago

    thanks, give the playground a go and let us know how to improve!

    • sroussey 2 hours ago

      I tried tweeking for structured extraction, but got issues with token budget. What is the context size?

forsalebypwner 4 hours ago

Any instructions available for running this on an ESP32-S3 or P4 like the site says?

  • rshemet 3 hours ago

    Hey! Roman here from Cactus - yes, we're putting putting together a detailed guide for ESP32.

    In the meantime, if you have enough RAM for the current model (≈28MB), our repo will get you up & running:

    https://github.com/cactus-compute/needle

ianseyler 4 hours ago

I’d be interested in attempting to run this in a network- enabled 32MiB RAM microVM.

yorwba 4 hours ago

"make it as dark as possible"

  {
    "function_calls": [
      {
        "name": "set_thermostat",
        "arguments": {
          "temperature": 72,
          "mode": "cool",
          "room": "living room"
        }
      }
    ],
    "reasoning": "'as dark as possible' -> set_thermostat to warm; 'dark' implies higher temperature; 'cool' mode for darkness.",
    "confidence": 0
  }

... maybe this counts as dark humor at least.

Since it seems limited to matching a few templates and otherwise falling flat on its face, I wonder how 14MB of regexes would fare in its stead. Normally you wouldn't want to parse arbitrary natural language input with regex because of how tedious and brittle it would be, but for the tedium we have LLMs and this alternative isn't exactly robust either.

platevoltage 1 hour ago

This is very interesting! I'm going to spend some time with this. This is really the only class of LLM I'm interested in at all. I sincerely hope on-device takes over and everyone looses their asses on these data centers.

varispeed 5 hours ago

What is the difference between this and random sentence generator?

  • HenryNdubuaku 5 hours ago

    Random sentence is not a function call.

  • actionfromafar 5 hours ago

    Ask it to lock a door for instance. It seems to convert simple instructions to reasonable tool calls. Check its confidence score.

yieldcrv 3 hours ago

what does the first L mean in LLM?

  • janalsncm 2 hours ago

    Fwiw people have told me that GPT2 doesn’t qualify as an LLM at 550MB despite being one of the first LLMs.

    So the practical answer to your question is: not much.

  • rshemet 1 minute ago

    it stands for Lets-not-be-sarcastic :)

grenli 4 hours ago

The learned confidence gate is the crucial piece for a 14MB action model. On ambiguous requests such as the HN example, what calibration target decides between abstaining locally and escalating to the cloud?

  • HenryNdubuaku 4 hours ago

    around +60% confidence threshold is cool from experiments, the problem is that you gotta test on your own workload, no existing benchmark could honestly paint the full picture, so we exposed the confidence threshold for everyone.