# Union Alpha Stealth Model

> Source: <https://developers.cloudflare.com/ai/models/stealth/union-alpha/>
> Published: 2026-09-17 06:04:36+00:00

- Third-party

Union Alpha is a multimodal model designed for research, coding, and agentic workflows. It delivers frontier-level performance across diverse general-purpose tasks.

```
Paris
```

## **System Guidance** — Set a helpful system role before asking a question.

```
An API (Application Programming Interface) is a set of rules that lets different software programs communicate with each other. For example, a weather app can use an API to request the latest forecast from a weather service.
```

## **Coding Example** — Ask for a short coding example.

javascript
function reverseString(str) {
  return [...str].reverse().join("");
}

// Example call:
console.log(reverseString("hello")); // "olleh"
## **Follow-up Conversation** — Continue a short conversation with prior assistant context.

```
Prioritize **location over amenities** for a short weekend—you’ll get more out of your trip if you spend less time in transit.

- **Your main activity:** Stay near the beach for a relaxing getaway, or near the center for restaurants, sightseeing, and nightlife.
- **Walkability and transport:** Look for cafés and dinner options within walking distance, plus easy access to the airport or train station. If you’re driving, check parking costs.
- **Total
```

## **Creative Writing** — Generate a compact piece of creative writing.

```
The weary day sank softly out of sight,
And left me searching shadows for a spark.
Then one small star unfolded into light—
Enough to lead me gently through the dark.
```

▶messages[]

`array` required
temperature

`number` minimum: 0maximum: 2
max_tokens

`number` exclusiveMinimum: 0
max_completion_tokens

`number` exclusiveMinimum: 0
top_p

`number` minimum: 0maximum: 1
frequency_penalty

`number` minimum: -2maximum: 2
presence_penalty

`number` minimum: -2maximum: 2
stream

`boolean`
▶stream_options{}

`object`
▶tools[]

`array`
tool_choice

response_format

▶modalities[]

`array`
▶audio{}

`object`
reasoning_effort

`string` Optional reasoning control; availability and accepted values are model-dependent.
id

`string`
object

`string`
created

`number`
model

`string`
▶choices[]

`array`
▶usage{}

`object`