"I've never seen anything scarier than an LLM with tool calls." — Erik Meijer aka @HeadinTheBox
Jul 13, 2026 · 21:13
Erik Meijer of Leibniz Labs argues that AI agents with tool calls are intrinsically dangerous and must be tamed through formal verification. He recounts how adding tool calls to LLMs turned harmless chatbots into agents capable of irreversible side effects, like deleting files or emptying bank accounts. His solution, implemented in Automind, uses proof-carrying code: the agent submits a plan as a program (Free Monad) together with a machine-checkable safety proof, and a small checker verifies the proof before allowing execution. This air-gaps the agent from its tools, ensuring policy compliance statically. Meijer demonstrates that elementary type systems and compiler techniques, such as taint analysis on program expressions, can provably prevent unsafe actions, turning agents from 'vibe-coding' risks into provably safe systems.
