Claude Agent SDK: Build Custom Agents with Ease

If you want to develop an Agent, whether CLI, Web, or Windows, consider using the Claude Agent SDK. It shares the same underlying code as Claude Code, which is essentially a CLI UI built on top of it. You can build your own Claude Code based on it. I recently built a simple Agent in a few hours: it takes input prompts, searches a design system's Markdown docs (hundreds of files) in an accessible directory, and uses the SDK's built-in Grep tool to find relevant component APIs, then generates UI based on that info. The SDK API is simple but powerful; you can use built-in tools (Task, Grep, WebFetch) or add your own, and even use MCP. It also exposes raw requests and responses via API, letting you build a better UI than the CLI. Limitations: 1) Only compatible with Claude models; using GPT-5 won't work well. 2) Only supports Python and TypeScript. 3) Tokens burn fast. If you're doing an early POC, I highly recommend trying it.