llama.cpp - tool calling issues on Windows only
Something is breaking tool calling in llama.cpp, but only on Windows. That specificity is what makes this worth paying attention to. The problem surfaced on April 28th in the LocalLLaMA community, where users reported that function-calling functionality — the mechanism that lets language models trigger external tools and APIs — was failing on Windows machines while presumably working fine on Linux and macOS. No patch has been publicly confirmed yet, and the thread hasn't lit up with enough signal to push this into higher confidence. The asymmetry is the story: when a bug respects operating system boundaries, it usually points to something in the build chain, path handling, or platform-specific library behavior rather than a logic error in the core model code. That narrows the search considerably, but it also means Windows users are currently running a version of llama.cpp where one of its most practically useful features simply doesn't work.
If confirmed, here is what this means. Tool calling isn't decorative — it's the feature that transforms a text generator into something that can actually do things, browse the web, query databases, run code. For the segment of the llama.cpp user base running Windows, which is substantial given that local AI hobbyists skew heavily toward consumer hardware running Microsoft's OS, this isn't a minor inconvenience. It's a functional regression that cuts off an entire class of use cases. Enterprise users quietly evaluating local LLM deployments on Windows infrastructure would be particularly affected. The second-order effect is subtler: bugs that only manifest on one platform tend to linger longer than universal ones, because the developers most likely to notice and fix them are the ones who happen to be running that platform.
Watch for a GitHub issue or pull request on the llama.cpp repository that specifically addresses Windows tool-calling behavior — that would either confirm the bug's scope or reveal it was narrower than initially reported.
<table> <tr><td> <a href="https://www.reddit.com/r/LocalLLaMA/comments/1s7z7hj/llamacpp_at_100k_stars/"> <img alt="llama.cpp at 100k stars"
<!-- SC_OFF --><div class="md"><p>I've been building llama.cpp in Windows 10 and Linux for over a year in a few computers, but now that I moved to a new one, with windows 10 and
<table> <tr><td> <a href="https://www.reddit.com/r/LocalLLaMA/comments/1vomycs/anyone_having_issues_with_ollama_post_v0321_with/"> <img alt="Anyone having issues with Ollama post
<!-- SC_OFF --><div class="md"><p>I am having trouble compiling the RPC server following the instructions here : <a
<!-- SC_OFF --><div class="md"><p>I've been using llama.cpp to run chatbots for a while now, everything works great. They have access to an MCP server with 22 tools which the
<!-- SC_OFF --><div class="md"><p>I’ve been testing LM Studio on my RTX 5070 Ti (16GB) and Ryzen 9800X3D, running Unsloth Qwen3.5 35B (UD Q4_K_XL).</p> <p>Initially, I thought LM
<!-- SC_OFF --><div class="md"><p>Hello People. I am new to these AI, LLM and programming and I want to Install claude code via llama cpp on Windows 10. I have Llama cpp
<!-- SC_OFF --><div class="md"><p>Anyone running into CUDA issues on newer GPUs (sm120)?</p> <p>Tried building llama.cpp with CUDA targeting sm_120 and couldn’t get a clean
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