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 capabilities to your agent sessions. A plugin can include:

Skills: capabilities Claude invokes autonomously when relevant. You can also invoke a plugin skill directly with /plugin-name:skill-name.
Agents: specialized subagents for specific tasks
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 type field must be "local", the only value the SDK accepts. The SDK supports loading multiple plugins from different locations. To use a plugin distributed through a marketplace or remote repository, download it first and provide the local directory path. For the directory layout a plugin needs, see the Plugin structure reference below.

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
}

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions


async def main():
    async for message in query(
        prompt="Hello",
        options=ClaudeAgentOptions(
            plugins=[
                {"type": "local", "path": "./my-plugin"},
                {"type": "local", "path": "/absolute/path/to/another-plugin"},
            ]
        ),
    ):
        # Plugin commands, agents, and other features are now available
        pass


asyncio.run(main())

Path specifications

Plugin paths can be:

Relative paths: resolved relative to your current working directory (for example, "./plugins/my-plugin")
Absolute paths: full file system paths (for example, "/home/user/plugins/my-plugin")

The path should point to the plugin’s root directory: the parent of skills/, agents/, hooks/, commands/, or .claude-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: "/absolute/path/to/my-plugin" }]

    // Plugin skills appear with the plugin name as a prefix
    console.log("Skills:", message.skills);
    // Example: ["my-plugin:greet"]

    // Plugin commands use the same prefix, and skills appear here too
    console.log("Commands:", message.slash_commands);
    // Example: ["compact", "context", "my-plugin:custom-command", "my-plugin:greet"]
  }
}

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions, SystemMessage


async def main():
    async for message in query(
        prompt="Hello",
        options=ClaudeAgentOptions(
            plugins=[{"type": "local", "path": "./my-plugin"}]
        ),
    ):
        if isinstance(message, SystemMessage) and message.subtype == "init":
            # Check loaded plugins
            print("Plugins:", message.data.get("plugins"))
            # Example: [{"name": "my-plugin", "path": "/absolute/path/to/my-plugin"}]

            # Plugin skills appear with the plugin name as a prefix
            print("Skills:", message.data.get("skills"))
            # Example: ["my-plugin:greet"]

            # Plugin commands use the same prefix, and skills appear here too
            print("Commands:", message.data.get("slash_commands"))
            # Example: ["compact", "context", "my-plugin:custom-command", "my-plugin:greet"]


asyncio.run(main())

Using plugin skills

Skills from plugins are automatically namespaced with the plugin name to avoid conflicts. To invoke one directly, send /plugin-name:skill-name as the prompt.

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

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

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions, AssistantMessage, TextBlock


async def main():
    # Load a plugin with a custom /greet skill
    async for message in query(
        prompt="/my-plugin:greet",  # Use plugin skill with namespace
        options=ClaudeAgentOptions(
            plugins=[{"type": "local", "path": "./my-plugin"}]
        ),
    ):
        # Claude executes the custom greeting skill from the plugin
        if isinstance(message, AssistantMessage):
            for block in message.content:
                if isinstance(block, TextBlock):
                    print(f"Claude: {block.text}")


asyncio.run(main())

If you installed a plugin via the CLI (for example, /plugin install my-plugin@marketplace), you can still use it in the SDK by providing its installation path. Check ~/.claude/plugins/ for CLI-installed plugins.

Complete example

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

import { query } from "@anthropic-ai/claude-agent-sdk";
import { fileURLToPath } from "node:url";

async function runWithPlugin() {
  const pluginPath = fileURLToPath(new URL("./plugins/my-plugin", import.meta.url));

  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 skills:", message.skills);
      console.log("Available commands:", message.slash_commands);
    }

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

runWithPlugin().catch(console.error);

#!/usr/bin/env python3
"""Example demonstrating how to use plugins with the Agent SDK."""

import asyncio
from pathlib import Path

from claude_agent_sdk import (
    AssistantMessage,
    ClaudeAgentOptions,
    SystemMessage,
    TextBlock,
    query,
)


async def run_with_plugin():
    """Example using a custom plugin."""
    plugin_path = Path(__file__).parent / "plugins" / "my-plugin"

    print(f"Loading plugin from: {plugin_path}")

    options = ClaudeAgentOptions(
        plugins=[{"type": "local", "path": str(plugin_path)}],
        max_turns=3,
    )

    async for message in query(
        prompt="What custom commands do you have available?", options=options
    ):
        if isinstance(message, SystemMessage) and message.subtype == "init":
            print(f"Loaded plugins: {message.data.get('plugins')}")
            print(f"Available skills: {message.data.get('skills')}")
            print(f"Available commands: {message.data.get('slash_commands')}")

        if isinstance(message, AssistantMessage):
            for block in message.content:
                if isinstance(block, TextBlock):
                    print(f"Assistant: {block.text}")


if __name__ == "__main__":
    asyncio.run(run_with_plugin())

Plugin structure reference

A plugin directory typically contains a .claude-plugin/plugin.json manifest file. The manifest is optional. When omitted, Claude Code auto-discovers components from the directory layout. The directory can include:

my-plugin/
├── .claude-plugin/
│   └── plugin.json          # Plugin manifest (optional, components auto-discovered without it)
├── skills/                   # Agent Skills (invoked autonomously or via /plugin-name:skill-name)
│   └── my-skill/
│       └── SKILL.md
├── commands/                 # Skills as flat .md files
│   └── custom-cmd.md
├── agents/                   # Custom agents
│   └── specialist.md
├── hooks/                    # Event handlers
│   └── hooks.json
└── .mcp.json                # MCP server definitions

The commands/ directory holds skills as flat Markdown files. Use skills/ for new plugins. Claude Code supports both locations.

Multiple plugin sources

Combine plugins from different locations:

import * as os from "node:os";
import * as path from "node:path";

plugins: [
  { type: "local", path: "./local-plugin" },
  {
    type: "local",
    path: path.join(os.homedir(), ".claude", "custom-plugins", "shared-plugin")
  }
];

The SDK doesn’t expand tilde paths like ~/plugins. If a plugin path doesn’t exist, the SDK skips that plugin and the session continues, so check the plugins list in the init message to confirm each plugin loaded.

Troubleshooting

Plugin not loading

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

Check the path: ensure the path points to the plugin root directory, the parent of skills/, agents/, hooks/, commands/, or .claude-plugin/
Validate plugin.json: if your plugin includes a manifest, ensure it has valid JSON syntax
Check file permissions: ensure the plugin directory is readable
Confirm the directory exists: the SDK skips a nonexistent path, and the plugin doesn’t appear in the init message’s plugins list

Skills not appearing

If plugin skills don’t work:

Use the namespace: invoke plugin skills as /plugin-name:skill-name
Check init message: verify the skill appears in the skills list with the correct namespace
Validate skill files: ensure each skill has a SKILL.md file in its own subdirectory under skills/, for example skills/my-skill/SKILL.md

Agent SDK

Build agents

Core concepts

Input and output

Extend with tools

Customize behavior

Control and observability

Deployment

SDK references

Loading plugins

Path specifications

Verifying plugin installation

Using plugin skills

Complete example

Plugin structure reference

Multiple plugin sources

Troubleshooting

Plugin not loading

Skills not appearing

See also

​Loading plugins

​Path specifications

​Verifying plugin installation

​Using plugin skills

​Complete example

​Plugin structure reference

​Multiple plugin sources

​Troubleshooting

​Plugin not loading

​Skills not appearing

​See also

Loading plugins

Path specifications

Verifying plugin installation

Using plugin skills

Complete example

Plugin structure reference

Multiple plugin sources

Troubleshooting

Plugin not loading

Skills not appearing

See also