Plugins

Plugins change the typical behavior of an agent. They let you introduce concepts like Skills, steering, or other behavioral modifications into the agent loop by composing on the low-level primitives the Agent class exposes—model, system_promptsystemPrompt, messages, tools, and hooks. Attach the built-in plugins the SDK ships, or write your own.

Extend your agent

SkillsGive the agent on-demand access to specialized instructions, following the AgentSkills specification.

Context OffloaderOffload oversized tool results to storage, leaving retrievable previews behind.

Context InjectorFold real-time text into the model input before each call, without persisting it to history.

GoalLoopValidate responses against a goal and loop with feedback until they satisfy it.

Build a custom pluginWrite your own plugin: register hooks and tools, manage state, and initialize it.

Attach a plugin

The smallest useful setup passes a plugin to an agent’s plugins list. The agent runs the plugin’s logic as part of its loop:

Python
TypeScript

from datetime import datetime, timezone

from strands import Agent
from strands.vended_plugins.context_injector import ContextInjector

agent = Agent(
    plugins=[
        ContextInjector(lambda context: f"<now>{datetime.now(timezone.utc).isoformat()}</now>"),
    ],
)
agent("What time is it right now?")

import { Agent } from '@strands-agents/sdk'
import { ContextInjector } from '@strands-agents/sdk/vended-plugins/context-injector'

const agent = new Agent({
  plugins: [
    new ContextInjector({
      renderContent: async () => `<now>${new Date().toISOString()}</now>`,
    }),
  ],
})

await agent.invoke('What time is it right now?')

From here you attach the plugins your application needs, or build your own.

Where to go next

New to plugins? Attach a built-in one from the grid above—Skills, Context Offloader, Context Injector, or GoalLoop—and see it change the agent’s behavior.

Ready to write your own? Build a custom plugin walks through registering hooks and tools, managing state, and async initialization. Hooks covers how the hook system works, and Hook events is the reference for every lifecycle event a plugin can react to.