> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hitheo.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Personas & E.V.I.

> Replace Theo's personality with your own branded AI assistant.

The `persona` parameter controls the base personality of every completion. An **E.V.I. (Embedded Virtual Intelligence)** is a pre-configured Theo client with a custom persona, skills, and tools baked in — your users interact with your brand, not Theo.

## Persona Options

| Value                      | Behavior                                                                                                                              |
| -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------- |
| `"theo"`                   | Theo's default personality — a sarcastic, brilliant robot from Jupiter. Witty, confident, and genuinely helpful underneath the snark. |
| `"none"`                   | Neutral assistant with no personality                                                                                                 |
| `{ system_prompt: "..." }` | Your custom persona — replaces Theo entirely                                                                                          |

```typescript theme={null}
// Custom persona
const res = await theo.complete({
  prompt: "Draft a follow-up email",
  persona: { system_prompt: "You are Eva, a professional CRM assistant for AcmeCorp." },
});
```

## E.V.I. — The SDK Shortcut

Instead of passing `persona`, `skills`, and `tools` on every request, create an E.V.I. instance:

```typescript theme={null}
const evi = theo.evi({
  persona: "You are Nova, an operations assistant for WarehouseOS. Professional, concise, proactive.",
  skills: ["inventory-check", "data-extraction"],
  tools: [
    {
      name: "check_stock",
      description: "Look up current stock levels for a SKU",
      input_schema: {
        type: "object",
        properties: { sku: { type: "string" } },
        required: ["sku"],
      },
    },
  ],
  defaultMode: "auto",
});

// Every call through the E.V.I. includes the persona, skills, and tools automatically
const res = await evi.complete({ prompt: "Check stock levels for SKU-1234" });
```

## Three Levels

1. **Persona only** — Replace Theo’s voice with your brand
2. **Persona + Skills** — Add domain expertise (inventory, compliance, etc.)
3. **Persona + Skills + Inline Tools** — Connect Theo to your product’s actions

See the full [E.V.I. Guide](/guides/build-an-evi) for detailed examples of each level.

## E.V.I. Canvas — The Visual Builder

Prefer a visual approach? The **E.V.I. Canvas** is a drag-and-drop skill builder in the dashboard. Design node graphs with prompts, models, tools, knowledge, vision, and conditions — then compile, test, and publish without writing a manifest.

See the [Canvas Guide](/guides/evi-canvas) and [Canvas SDK Reference](/sdk-reference/canvases).