The smartest AI agents today are all built on one key idea: the Claude Agent SDK Loop.
It’s the framework behind Claude Code, and it’s quickly becoming the go-to way to build powerful and reliable AI agents.
Here’s how it works:
1. Gather Context
Pull in the right information using subagents that can work in parallel. Keep context compact, use semantic or hybrid search to find what’s relevant, and make sure your agent always has what it needs to reason clearly. For coding agents, hybrid search works especially well.
2. Take Action
Once the agent understands the problem, it takes action. It can use tools, MCP servers, or simple bash scripts. It can even generate and run code to get results. With code execution and routing, agents run faster and use far fewer tokens, much like model routing makes LLMs more efficient.
3. Verify Output
After acting, the agent checks its own work. You can define rules, use visual feedback for multimodal tasks, or let an LLM act as a judge for quality. The key is simplicity; don’t overbuild when a smart script or Skill can handle it.
The Claude Agent SDK Loop is more than a framework; it’s a simple, flexible way to build AI agents that can think, act, and improve in any domain.