I Gave My AI a Toolbox — It Surprised Me by Using It

A 3.5MB Go binary was sitting in my source tree, staged for commit. git log showed nothing — it had never been committed. I had no idea how it got there. I asked Claude Code to investigate. I didn't point it to any specific tool. I didn't tell it how to search. I just said: "There's a mystery binary in the repo. Where did it come from?" It solved the mystery in under a minute — using a tool I'd forgotten I built. But that's getting ahead of the story. This is Part 3 of the AI Sandbox series. Part 1 introduced the AI Sandbox and secret hiding. Part 2 positioned it against official Docker and Claude Code sandboxes. This article focuses on what happens inside the sandbox — specifically, what AI does when you give it the ability to discover tools on its own. Drop a File, Get a Tool Inside the AI Sandbox — a Docker-based environment where AI coding agents run in isolation — I wanted a simple way to extend what AI can do. Not by editing config files or registering MCP servers for every new c