Plugins in the SDK

Plugins allow you to extend Claude Code with custom functionality that can be shared across projects. Through the Agent SDK, you can programmatically load plugins from local directories to add custom slash commands, agents, skills, hooks, and MCP servers to your agent sessions.

What are plugins?

Plugins are packages of Claude Code extensions that can include:

• Commands: Custom slash commands
• Agents: Specialized subagents for specific tasks
• Skills: Model-invoked capabilities that Claude uses autonomously
• Hooks: Event handlers that respond to tool use and other events
• MCP servers: External tool integrations via Model Context Protocol

For complete information on plugin structure and how to create plugins, see Plugins.

Loading plugins

Load plugins by providing their local file system paths in your options configuration. The SDK supports loading multiple plugins from different locations.

import { query } from "@anthropic-ai/claude-agent-sdk";

for await (const message of query({
  prompt: "Hello",
  options: {
    plugins: [
      { type: "local", path: "./my-plugin" },
      { type: "local", path: "/absolute/path/to/another-plugin" }
    ]
  }
})) {
  // Plugin commands, agents, and other features are now available
}

Path specifications

Plugin paths can be:

• Relative paths: Resolved relative to your current working directory (e.g., "./plugins/my-plugin")
• Absolute paths: Full file system paths (e.g., "/home/user/plugins/my-plugin")

Verifying plugin installation

When plugins load successfully, they appear in the system initialization message. You can verify that your plugins are available:

import { query } from "@anthropic-ai/claude-agent-sdk";

for await (const message of query({
  prompt: "Hello",
  options: {
    plugins: [{ type: "local", path: "./my-plugin" }]
  }
})) {
  if (message.type === "system" && message.subtype === "init") {
    // Check loaded plugins
    console.log("Plugins:", message.plugins);
    // Example: [{ name: "my-plugin", path: "./my-plugin" }]

    // Check available commands from plugins
    console.log("Commands:", message.slash_commands);
    // Example: ["/help", "/compact", "my-plugin:custom-command"]
  }
}

Using plugin commands

Commands from plugins are automatically namespaced with the plugin name to avoid conflicts. The format is plugin-name:command-name.

import { query } from "@anthropic-ai/claude-agent-sdk";

// Load a plugin with a custom /greet command
for await (const message of query({
  prompt: "/my-plugin:greet",  // Use plugin command with namespace
  options: {
    plugins: [{ type: "local", path: "./my-plugin" }]
  }
})) {
  // Claude executes the custom greeting command from the plugin
  if (message.type === "assistant") {
    console.log(message.content);
  }
}

Complete example

Here's a full example demonstrating plugin loading and usage:

import { query } from "@anthropic-ai/claude-agent-sdk";
import * as path from "path";

async function runWithPlugin() {
  const pluginPath = path.join(__dirname, "plugins", "my-plugin");

  console.log("Loading plugin from:", pluginPath);

  for await (const message of query({
    prompt: "What custom commands do you have available?",
    options: {
      plugins: [
        { type: "local", path: pluginPath }
      ],
      maxTurns: 3
    }
  })) {
    if (message.type === "system" && message.subtype === "init") {
      console.log("Loaded plugins:", message.plugins);
      console.log("Available commands:", message.slash_commands);
    }

    if (message.type === "assistant") {
      console.log("Assistant:", message.content);
    }
  }
}

runWithPlugin().catch(console.error);

Plugin structure reference

A plugin directory must contain a .claude-plugin/plugin.json manifest file. It can optionally include:

my-plugin/
├── .claude-plugin/
│   └── plugin.json          # Required: plugin manifest
├── commands/                 # Custom slash commands
│   └── custom-cmd.md
├── agents/                   # Custom agents
│   └── specialist.md
├── skills/                   # Agent Skills
│   └── my-skill/
│       └── SKILL.md
├── hooks/                    # Event handlers
│   └── hooks.json
└── .mcp.json                # MCP server definitions

For detailed information on creating plugins, see:

• Plugins - Complete plugin development guide
• Plugins reference - Technical specifications and schemas

Common use cases

Development and testing

Load plugins during development without installing them globally:

plugins: [
  { type: "local", path: "./dev-plugins/my-plugin" }
]

Project-specific extensions

Include plugins in your project repository for team-wide consistency:

plugins: [
  { type: "local", path: "./project-plugins/team-workflows" }
]

Multiple plugin sources

Combine plugins from different locations:

plugins: [
  { type: "local", path: "./local-plugin" },
  { type: "local", path: "~/.claude/custom-plugins/shared-plugin" }
]

Troubleshooting

Plugin not loading

If your plugin doesn't appear in the init message:

1. Check the path: Ensure the path points to the plugin root directory (containing .claude-plugin/)
2. Validate plugin.json: Ensure your manifest file has valid JSON syntax
3. Check file permissions: Ensure the plugin directory is readable

Commands not available

If plugin commands don't work:

1. Use the namespace: Plugin commands require the plugin-name:command-name format
2. Check init message: Verify the command appears in slash_commands with the correct namespace
3. Validate command files: Ensure command markdown files are in the commands/ directory

Path resolution issues

If relative paths don't work:

1. Check working directory: Relative paths are resolved from your current working directory
2. Use absolute paths: For reliability, consider using absolute paths
3. Normalize paths: Use path utilities to construct paths correctly

See also

• Plugins - Complete plugin development guide
• Plugins reference - Technical specifications
• Slash Commands - Using slash commands in the SDK
• Subagents - Working with specialized agents
• Skills - Using Agent Skills