Claude agent vs Claude Code: which one are you actually building?

Search "claude agent boilerplate" and you'll drown in Claude Code results — the agentic CLI, CLAUDE.md files, slash commands, hooks. Great tools. But none of that is what you want if you're trying to build your own agent on the Anthropic SDK.

Here's the disambiguation, and the ~40 lines that are actually the whole thing.

Two different "Claude agents"

Claude Code — Anthropic's agentic coding CLI. You configure it; you don't build it.

An agent you build — your app calls the Anthropic SDK in a loop: the model asks for a tool, you run it, feed the result back, repeat until it's done. That loop is the agent.