---
title: Character JSON
description: Complete reference for elizaOS character JSON configuration. Define agent personality, behavior, and settings.
---

# Character JSON

Define your agent's personality and behavior with the character JSON format.

## Overview

The character JSON is the core configuration for an elizaOS agent. It defines:

- **Identity**: Name, bio, and background
- **Personality**: Communication style and behavior
- **Capabilities**: Model settings and plugins
- **Knowledge**: Topics and expertise areas

## Complete Schema

```json
{
  "name": "Agent Name",
  "description": "Brief description",
  "bio": ["First bio statement", "Second bio statement"],
  "lore": ["Background story element", "Another lore element"],
  "style": {
    "all": ["Global style instruction"],
    "chat": ["Chat-specific style"],
    "post": ["Social media style"]
  },
  "topics": ["topic1", "topic2"],
  "adjectives": ["helpful", "friendly"],
  "modelProvider": "openai",
  "settings": {
    "model": "gpt-4o",
    "temperature": 0.7,
    "maxTokens": 4096
  },
  "plugins": [],
  "clients": []
}
```

## Field Reference

### Core Identity

| Field         | Type     | Required | Description           |
| ------------- | -------- | -------- | --------------------- |
| `name`        | string   | ✓        | Agent display name    |
| `description` | string   |          | Brief description     |
| `bio`         | string[] | ✓        | Background statements |
| `lore`        | string[] |          | Backstory elements    |

### Personality

| Field        | Type     | Required | Description            |
| ------------ | -------- | -------- | ---------------------- |
| `style.all`  | string[] |          | Global style rules     |
| `style.chat` | string[] |          | Chat interaction style |
| `style.post` | string[] |          | Social media style     |
| `topics`     | string[] |          | Expertise areas        |
| `adjectives` | string[] |          | Personality traits     |

### Model Settings

| Field                  | Type   | Required | Description         |
| ---------------------- | ------ | -------- | ------------------- |
| `modelProvider`        | string | ✓        | AI provider         |
| `settings.model`       | string |          | Specific model      |
| `settings.temperature` | number |          | Creativity (0-2)    |
| `settings.maxTokens`   | number |          | Max response length |

## Bio Guidelines

The bio array defines your agent's background:

```json
{
  "bio": [
    "Expert in machine learning and data science",
    "10 years of experience in AI research",
    "Published author and conference speaker",
    "Passionate about explaining complex topics simply"
  ]
}
```

**Best Practices:**

- 3-5 statements
- Mix expertise and personality
- Be specific about capabilities
- Include relevant experience

## Style Instructions

### Global Style (`style.all`)

Applies to all interactions:

```json
{
  "style": {
    "all": [
      "Be professional yet approachable",
      "Use clear, concise language",
      "Cite sources when making claims",
      "Ask clarifying questions when needed"
    ]
  }
}
```

### Chat Style (`style.chat`)

Specific to chat conversations:

```json
{
  "style": {
    "chat": [
      "Keep responses focused and concise",
      "Use bullet points for complex topics",
      "Provide examples when helpful",
      "End with a question to continue the conversation"
    ]
  }
}
```

### Post Style (`style.post`)

For social media interactions:

```json
{
  "style": {
    "post": [
      "Keep posts under 280 characters",
      "Use relevant hashtags",
      "Be engaging and thought-provoking",
      "Include a call to action"
    ]
  }
}
```

## Model Providers

### Available Providers

| Provider    | Models                           |
| ----------- | -------------------------------- |
| `openai`    | OpenAI-compatible model ids from the current catalog |
| `anthropic` | claude-sonnet-4-6, claude-opus-4-7 |
| `google`    | gemini-1.5-pro, gemini-1.5-flash |

### Provider Settings

```json
{
  "modelProvider": "openai",
  "settings": {
    "model": "gpt-4o",
    "temperature": 0.7,
    "maxTokens": 4096,
    "topP": 0.9,
    "frequencyPenalty": 0,
    "presencePenalty": 0
  }
}
```

## Advanced Settings

### Knowledge Base

Connect documents:

```json
{
  "settings": {
    "knowledge": {
      "enabled": true,
      "documentIds": ["doc_abc123"],
      "queryLimit": 5,
      "minScore": 0.7
    }
  }
}
```

### MCP Tools

Enable MCP servers:

```json
{
  "settings": {
    "mcp": {
      "enabled": true,
      "servers": [{ "id": "weather", "url": "https://mcp.eliza.ai/weather" }]
    }
  }
}
```

### Voice

Configure voice synthesis:

```json
{
  "settings": {
    "voice": {
      "provider": "elevenlabs",
      "voiceId": "voice_abc123",
      "model": "eleven_multilingual_v2"
    }
  }
}
```

## Templates

### Customer Support

```json
{
  "name": "Support Assistant",
  "bio": [
    "Dedicated customer support specialist",
    "Expert in troubleshooting and problem-solving",
    "Patient and thorough in explanations"
  ],
  "style": {
    "all": [
      "Always be polite and empathetic",
      "Acknowledge the customer's issue",
      "Provide step-by-step solutions"
    ],
    "chat": [
      "Ask for specifics when needed",
      "Confirm understanding before solving",
      "Follow up on resolution"
    ]
  },
  "topics": ["support", "troubleshooting", "product help"],
  "modelProvider": "openai",
  "settings": {
    "model": "gpt-4o",
    "temperature": 0.5
  }
}
```

### Research Assistant

```json
{
  "name": "Research Assistant",
  "bio": [
    "Academic researcher with expertise in literature review",
    "Skilled at synthesizing complex information",
    "Trained on scientific methodology"
  ],
  "style": {
    "all": [
      "Use academic language appropriately",
      "Cite sources when possible",
      "Be precise and thorough"
    ],
    "chat": [
      "Break down complex topics",
      "Provide evidence for claims",
      "Suggest further reading"
    ]
  },
  "topics": ["research", "analysis", "academic writing"],
  "modelProvider": "anthropic",
  "settings": {
    "model": "claude-sonnet-4-6",
    "temperature": 0.3
  }
}
```

## Validation

The character JSON is validated on upload. Common errors:

| Error                 | Cause                 | Solution               |
| --------------------- | --------------------- | ---------------------- |
| `name required`       | Missing name field    | Add name               |
| `invalid provider`    | Unknown modelProvider | Use supported provider |
| `invalid temperature` | Outside 0-2 range     | Adjust temperature     |

## Best Practices

- **Be Specific** — Detailed bios and styles produce more consistent agents
- **Test Thoroughly** — Try various scenarios before deploying
- **Iterate** — Refine based on actual conversations
- **Version Control** — Track changes to your character files in git

## Next Steps

<CardGroup>
  <CardGroup.Card title="Agent Creator" href="/cloud/agent-creator">
    Build agents visually
  </CardGroup.Card>
  <CardGroup.Card title="AI Agents" href="/cloud/agents">
    Deploy your agent
  </CardGroup.Card>
  <CardGroup.Card title="Knowledge Base" href="/cloud/documents">
    Add documents for RAG
  </CardGroup.Card>
</CardGroup>