Claude Agent SDK Plugins: You Built a Test Tool, a Reviewer, and an Audit Hook.

Anthropic's Claude Agent SDK now supports plugins that bundle custom tools, subagents, hooks, and MCP servers into a single portable directory, loading with one line of config. This eliminates the need to manually wire scattered extensions across projects. The feature is detailed in Part 11 of a 14-part guide on building with the SDK.

Member-only story Claude Agent SDK Plugins: You Built a Test Tool, a Reviewer, and an Audit Hook. Stop Wiring Them by Hand. Part 11: How Claude Agent SDK plugins bundle the custom tools, subagents, hooks, and MCP servers you have scattered across your code into one portable directory that loads in a single line of config. You built useful extensions for your agent, but they live in five different places and you re-wire them by hand every time you start a new project. Custom tools, subagents, hooks, and MCP servers do not have to stay scattered across your code. A Claude Agent SDK plugin bundles all four into one portable directory that loads with a single line of config. In this article: You will learn what a Claude Agent SDK plugin actually is, how it differs from on-disk config, and how to load one correctly. We cover the canonical plugin layout, the one verification step that saves you an afternoon of confusion, the namespace rule that makes skills look broken when you miss it, and a worked example that packages a real agent’s tools into a single portable unit. By the end, your whole agent travels as one directory. Part 11 of “Building with the Claude Agent SDK,” a 14-part guide to building https://rickhigh.substack.com/p/claude-agent-sdk-plugins-you-built …