Components - ElizaOS Documentation

Overview

Plugin components are the building blocks that give agents their capabilities. Each component type serves a specific purpose in the agent’s decision-making and interaction flow. For system architecture, see Plugin Architecture.

Component Types

Component	Purpose	When Executed
Actions	Tasks agents can perform	When agent decides to take action
Providers	Supply contextual data	Before actions/decisions
Evaluators	Process and extract from responses	After agent generates response
Services	Manage stateful connections	Throughout agent lifecycle

Actions

Actions are discrete tasks agents can perform. They represent the agent’s capabilities - what it can DO.

Action Interface

Actions define discrete tasks that agents can perform. Each action has:

name: Unique identifier for the action
description: Clear explanation of what the action does
similes: Alternative names or aliases for fuzzy matching
examples: Training examples showing when to use the action
validate: Function to check if the action can run in the current context
handler: The execution logic that returns an ActionResult

The handler receives the runtime, message, state, options (for action chaining), an optional callback for intermediate responses, and previous responses. Important: All action handlers must return an ActionResult with a success field indicating whether the action completed successfully. For complete interface definitions, see Plugin Reference.

Core Actions (Bootstrap Plugin)

The bootstrap plugin provides 13 essential actions:

Communication Actions

Action	Description	Example Trigger
`REPLY`	Generate response	”Tell me about…”
`SEND_MESSAGE`	Send to specific room	”Message the team…”
`NONE`	Acknowledge silently	”Thanks!”
`IGNORE`	Skip message	Spam/irrelevant

Room Management

Action	Description	Example Trigger
`FOLLOW_ROOM`	Subscribe to updates	”Join #general”
`UNFOLLOW_ROOM`	Unsubscribe	”Leave #general”
`MUTE_ROOM`	Mute notifications	”Mute this channel”
`UNMUTE_ROOM`	Unmute	”Unmute #general”

Data & Configuration

Action	Description	Example Trigger
`UPDATE_CONTACT`	Update contact info	”Remember that I…”
`UPDATE_ROLE`	Change roles	”Make me admin”
`UPDATE_SETTINGS`	Modify settings	”Set model to gpt-4”

Media & Utilities

Action	Description	Example Trigger
`GENERATE_IMAGE`	Create AI images	”Draw a cat”
`CHOICE`	Present options	”Should I A or B?”

Creating Actions

For advanced patterns, see Plugin Patterns.

Minimal Action

const action: Action = {
  name: 'MY_ACTION',
  description: 'Does something',
  validate: async () => true,
  handler: async (runtime, message) => {
    return { 
      success: true,  // REQUIRED
      text: "Done!" 
    };
  }
};

With Validation

const sendTokenAction: Action = {
  name: 'SEND_TOKEN',
  description: 'Send tokens to address',
  
  validate: async (runtime, message) => {
    return message.content.includes('send') && 
           message.content.includes('0x');
  },
  
  handler: async (runtime, message) => {
    const address = extractAddress(message.content);
    const amount = extractAmount(message.content);
    await sendToken(address, amount);
    return {
      success: true,
      text: `Sent ${amount} tokens to ${address}`
    };
  }
};

With Examples

const action: Action = {
  name: 'WEATHER',
  description: 'Get weather info',
  examples: [[
    { name: "user", content: { text: "What's the weather?" } },
    { name: "agent", content: { text: "Let me check the weather for you." } }
  ]],
  validate: async (runtime, message) => {
    return message.content.toLowerCase().includes('weather');
  },
  handler: async (runtime, message) => {
    const weather = await fetchWeather();
    return { 
      success: true,
      text: `It's ${weather.temp}°C and ${weather.condition}` 
    };
  }
};

Handler Patterns

// Using callbacks
handler: async (runtime, message, state, options, callback) => {
  const result = await doWork();
  if (callback) {
    await callback({ text: result }, []);
  }
  return { success: true, text: result };
}

// Using services
handler: async (runtime, message) => {
  const service = runtime.getService<TwitterService>('twitter');
  return service.post(message.content);
}

// Using database
handler: async (runtime, message) => {
  const memories = await runtime.databaseAdapter.searchMemories({
    query: message.content,
    limit: 5
  });
  return { success: true, data: { memories } };
}

Best Practices for Actions

Name actions clearly (VERB_NOUN format)
Always return ActionResult with success field
Validate before executing
Return consistent response format
Use similes for alternative triggers
Provide diverse examples
Handle errors gracefully

Providers

Providers supply contextual information to the agent’s state before it makes decisions. They act as the agent’s “senses”, gathering relevant data.

Provider Interface

Providers supply contextual data to enhance agent decision-making. Each provider has:

name: Unique identifier for the provider
description: Optional explanation of what data it provides
dynamic: If true, data is re-fetched each time (not cached)
position: Execution order priority (-100 to 100, lower runs first)
private: If true, hidden from the default provider list
get: Function that returns a ProviderResult with text, values, and data

The get function receives the runtime, current message, and state, returning data that will be composed into the agent’s context. For complete interface definitions, see the Provider Interface in the Reference.

Core Providers (Bootstrap Plugin)

Provider	Returns	Example Use
`characterProvider`	Agent personality	Name, bio, traits
`timeProvider`	Current date/time	”What time is it?”
`knowledgeProvider`	Knowledge base	Documentation, facts
`recentMessagesProvider`	Chat history	Context awareness
`actionsProvider`	Available actions	”What can you do?”
`factsProvider`	Stored facts	User preferences
`settingsProvider`	Configuration	Model settings

Creating Providers

Basic Provider

const provider: Provider = {
  name: 'MY_DATA',
  get: async (runtime, message, state) => {
    return {
      text: "Contextual information",
      data: { key: "value" }
    };
  }
};

Dynamic Provider

const dynamicProvider: Provider = {
  name: 'LIVE_DATA',
  dynamic: true,  // Re-fetched each time
  get: async (runtime) => {
    const data = await fetchLatestData();
    return { data };
  }
};

Private Provider

const secretProvider: Provider = {
  name: 'INTERNAL_STATE',
  private: true,  // Not shown in provider list
  get: async (runtime) => {
    return runtime.getInternalState();
  }
};

Provider Priority

// Lower numbers = higher priority
position: -100  // Loads first
position: 0     // Default
position: 100   // Loads last

Provider Execution Flow

Providers are executed during runtime.composeState()
By default, all non-private, non-dynamic providers are included
Providers are sorted by position and executed in order
Results are aggregated into a unified state object
The composed state is passed to actions and the LLM for decision-making

Best Practices for Providers

Return consistent data structures
Handle errors gracefully
Cache when appropriate
Keep data fetching fast
Document what data is provided
Use position to control execution order

Evaluators

Evaluators are post-processors that analyze and extract information from conversations.

Evaluator Interface

Evaluators process and extract information from agent responses. Each evaluator has:

name: Unique identifier for the evaluator
description: Explanation of what it evaluates or extracts
similes: Alternative names for matching
alwaysRun: If true, runs on every agent response
examples: Training examples for the evaluator
validate: Function to determine if evaluator should run
handler: Processing logic that analyzes the response

Evaluators run after an agent generates a response, allowing for fact extraction, sentiment analysis, or content filtering. For complete interface definitions, see the Evaluator Interface in the Reference.

Core Evaluators (Bootstrap Plugin)

Evaluator	Purpose	Extracts
`reflectionEvaluator`	Self-awareness	Insights about interactions
`factEvaluator`	Fact extraction	Important information
`goalEvaluator`	Goal tracking	User objectives

Evaluator Flow

Common Use Cases

Memory Building

Extract facts from conversations
Track user preferences
Update relationship status
Record important events

Content Filtering

Remove sensitive data
Filter profanity
Ensure compliance
Validate accuracy

Analytics

Track sentiment
Measure engagement
Monitor topics
Analyze patterns

Creating Evaluators

Basic Evaluator

const evaluator: Evaluator = {
  name: 'my-evaluator',
  description: 'Processes responses',
  examples: [],  // Training examples
  
  validate: async (runtime, message) => {
    return true;  // Run on all messages
  },
  
  handler: async (runtime, message) => {
    // Process and extract
    const result = await analyze(message);
    // Store findings
    await storeResult(result);
    return result;
  }
};

With Examples

const evaluator: Evaluator = {
  name: 'fact-extractor',
  description: 'Extracts facts from conversations',
  examples: [{
    prompt: 'Extract facts from this conversation',
    messages: [
      { name: 'user', content: { text: 'I live in NYC' } },
      { name: 'agent', content: { text: 'NYC is a great city!' } }
    ],
    outcome: 'User lives in New York City'
  }],
  validate: async () => true,
  handler: async (runtime, message, state) => {
    const facts = await extractFacts(state);
    for (const fact of facts) {
      await runtime.factsManager.addFact(fact);
    }
    return facts;
  }
};

Best Practices for Evaluators

Run evaluators async (don’t block responses)
Store extracted data for future context
Use alwaysRun: true sparingly
Provide clear examples for training
Keep handlers lightweight

Services

Services manage stateful connections and provide core functionality. They are singleton instances that persist throughout the agent’s lifecycle.

Service Abstract Class

Services are singleton instances that manage stateful connections and provide persistent functionality throughout the agent’s lifecycle. Services extend an abstract class with:

serviceType: Static property identifying the service type
capabilityDescription: Description of what the service provides
start(): Static method to initialize and start the service
stop(): Method to clean up resources when shutting down
config: Optional configuration metadata

Services are ideal for managing database connections, API clients, WebSocket connections, or any long-running background tasks. For the complete Service class definition, see the Service Abstract Class in the Reference.

Service Types

The system includes predefined service types:

TRANSCRIPTION, VIDEO, BROWSER, PDF
REMOTE_FILES (AWS S3)
WEB_SEARCH, EMAIL, TEE
TASK, WALLET, LP_POOL, TOKEN_DATA
DATABASE_MIGRATION
PLUGIN_MANAGER, PLUGIN_CONFIGURATION, PLUGIN_USER_INTERACTION

Creating Services

import { Service, IAgentRuntime, logger } from '@elizaos/core';

export class MyService extends Service {
  static serviceType = 'my-service';
  capabilityDescription = 'Description of what this service provides';

  private client: any;
  private refreshInterval: NodeJS.Timer | null = null;

  constructor(protected runtime: IAgentRuntime) {
    super();
  }

  static async start(runtime: IAgentRuntime): Promise<MyService> {
    logger.info('Initializing MyService');
    const service = new MyService(runtime);

    // Initialize connections, clients, etc.
    await service.initialize();

    // Set up periodic tasks if needed
    service.refreshInterval = setInterval(
      () => service.refreshData(),
      60000 // 1 minute
    );

    return service;
  }

  async stop(): Promise<void> {
    // Cleanup resources
    if (this.refreshInterval) {
      clearInterval(this.refreshInterval);
    }
    // Close connections
    if (this.client) {
      await this.client.disconnect();
    }
    logger.info('MyService stopped');
  }

  private async initialize(): Promise<void> {
    // Service initialization logic
    const apiKey = this.runtime.getSetting('MY_API_KEY');
    if (!apiKey) {
      throw new Error('MY_API_KEY not configured');
    }

    this.client = new MyClient({ apiKey });
    await this.client.connect();
  }
}

Service Lifecycle Patterns

Delayed Initialization

Sometimes services need to wait for other services or perform startup tasks:

export class MyService extends Service {
  static serviceType = 'my-service';

  static async start(runtime: IAgentRuntime): Promise<MyService> {
    const service = new MyService(runtime);

    // Immediate initialization
    await service.initialize();

    // Delayed initialization for non-critical tasks
    setTimeout(async () => {
      try {
        await service.loadCachedData();
        await service.syncWithRemote();
        logger.info('MyService: Delayed initialization complete');
      } catch (error) {
        logger.error('MyService: Delayed init failed', error);
        // Don't throw - service is still functional
      }
    }, 5000);

    return service;
  }
}

Best Practices for Services

Handle missing API tokens gracefully
Implement proper cleanup in stop()
Use delayed initialization for non-critical tasks
Log service lifecycle events
Make services resilient to failures
Keep service instances stateless when possible

Component Interaction

Execution Flow

Providers gather context → compose state
Actions validate against state → execute if valid
Evaluators process responses → extract information
Services provide persistent functionality throughout

State Composition

// Providers contribute to state
const state = await runtime.composeState(message, [
  'RECENT_MESSAGES',
  'CHARACTER',
  'KNOWLEDGE'
]);

// Actions receive composed state
const result = await action.handler(runtime, message, state);

// Evaluators process with full context
await evaluator.handler(runtime, message, state);

Service Access

// Actions and providers can access services
const service = runtime.getService<MyService>('my-service');
const data = await service.getData();

Plugin Example with All Components

import type { Plugin } from '@elizaos/core';

export const myPlugin: Plugin = {
  name: 'my-complete-plugin',
  description: 'Example plugin with all component types',
  
  services: [MyService],
  
  actions: [{
    name: 'MY_ACTION',
    description: 'Performs an action using the service',
    validate: async (runtime) => {
      return runtime.getService('my-service') !== null;
    },
    handler: async (runtime, message) => {
      const service = runtime.getService<MyService>('my-service');
      const result = await service.doSomething();
      return { success: true, text: result };
    }
  }],
  
  providers: [{
    name: 'MY_PROVIDER',
    get: async (runtime) => {
      const service = runtime.getService<MyService>('my-service');
      const data = await service.getCurrentState();
      return {
        text: `Current state: ${JSON.stringify(data)}`,
        data
      };
    }
  }],
  
  evaluators: [{
    name: 'MY_EVALUATOR',
    description: 'Extracts relevant information',
    examples: [],
    validate: async () => true,
    handler: async (runtime, message) => {
      const extracted = await extractInfo(message);
      await runtime.storeExtracted(extracted);
      return extracted;
    }
  }]
};

Guide: Create a Plugin

What’s Next?

Plugin Architecture

Understand overall plugin system design

Development Guide

Build your first plugin step by step

Common Patterns

Learn proven plugin development patterns

Plugin Reference

Complete API reference for all interfaces

GETTING STARTED

GUIDES

PROJECTS

AGENTS

PLUGINS

RUNTIME

​Overview

​Component Types

​Actions

​Action Interface

​Core Actions (Bootstrap Plugin)

​Communication Actions

​Room Management

​Data & Configuration

​Media & Utilities

​Creating Actions

​Minimal Action

​With Validation

​With Examples

​Handler Patterns

​Best Practices for Actions

​Providers

​Provider Interface

​Core Providers (Bootstrap Plugin)

​Creating Providers

​Basic Provider

​Dynamic Provider

​Private Provider

​Provider Priority

​Provider Execution Flow

​Best Practices for Providers

​Evaluators

​Evaluator Interface

​Core Evaluators (Bootstrap Plugin)

​Evaluator Flow

​Common Use Cases

​Memory Building

​Content Filtering

​Analytics

​Creating Evaluators

​Basic Evaluator

​With Examples

​Best Practices for Evaluators

​Services

​Service Abstract Class

​Service Types

​Creating Services

​Service Lifecycle Patterns

​Delayed Initialization

​Best Practices for Services

​Component Interaction

​Execution Flow

​State Composition

​Service Access

​Plugin Example with All Components

​What’s Next?

Plugin Architecture

Development Guide

Common Patterns

Plugin Reference

Overview

Component Types

Actions

Action Interface

Core Actions (Bootstrap Plugin)

Communication Actions

Room Management

Data & Configuration

Media & Utilities

Creating Actions

Minimal Action

With Validation

With Examples

Handler Patterns

Best Practices for Actions

Providers

Provider Interface

Core Providers (Bootstrap Plugin)

Creating Providers

Basic Provider

Dynamic Provider

Private Provider

Provider Priority

Provider Execution Flow

Best Practices for Providers

Evaluators

Evaluator Interface

Core Evaluators (Bootstrap Plugin)

Evaluator Flow

Common Use Cases

Memory Building

Content Filtering

Analytics

Creating Evaluators

Basic Evaluator

With Examples

Best Practices for Evaluators

Services

Service Abstract Class

Service Types

Creating Services

Service Lifecycle Patterns

Delayed Initialization

Best Practices for Services

Component Interaction

Execution Flow

State Composition

Service Access

Plugin Example with All Components

What’s Next?