# Step 5 Preview

Canonical page: https://agentsky.dev/models/stepfun/step-5-preview
JSON record: https://gateway.agentsky.dev/v1/models/stepfun/step-5-preview

Step 5 Preview is a text and image and video-input model by Stepfun, available through the AgentSky API as stepfun/step-5-preview at $1.1605 per million input tokens and $3.13335 per million output tokens, with a 1M context window.

Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters).

## Facts

- **Model id:** `stepfun/step-5-preview`
- **Maker:** Stepfun
- **Input modalities:** Text, Image, Video
- **Context:** 1M
- **Max output tokens:** 64,000
- **Aliases:** `stepfun/step-5-preview`, `step-5-preview`

## Pricing

USD per million tokens on the default plan. Signed-in pages show your own plan's price; every response carries the cost of that call in `usage.cost`.

| Meter | Per 1M tokens |
|---|---|
| Input | $1.1605 |
| Output | $3.13335 |
| Cache read | $0.11605 |
| Cache write | $1.1605 |

## Use it

Anthropic wire base URL: `https://gateway.agentsky.dev`. OpenAI wire base URL: `https://gateway.agentsky.dev/v1`. Authenticate with an AgentSky API key (`ast_…`) and pass the model id.

### OpenAI SDK

```js
import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://gateway.agentsky.dev/v1",
  apiKey: process.env.AGENTSKY_API_KEY, // ast_…
});

const completion = await client.chat.completions.create({
  model: "stepfun/step-5-preview",
  messages: [{ role: "user", content: "Summarise this ticket." }],
});
console.log(completion.usage.cost); // USD, in the response
```

### Codex

```bash
export OPENAI_BASE_URL="https://gateway.agentsky.dev/v1"
export OPENAI_API_KEY="$AGENTSKY_API_KEY"

codex --model stepfun/step-5-preview
```

### OpenCode

```js
// opencode.json — then switch models any time with /models
{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "agentsky": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "AgentSky",
      "options": {
        "baseURL": "https://gateway.agentsky.dev/v1",
        "apiKey": "{env:AGENTSKY_API_KEY}"
      },
      "models": { "stepfun/step-5-preview": {} }
    }
  }
}
```

## Questions

### What is Step 5 Preview?

Step 5 Preview is a model from Stepfun. Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters).

### How much does Step 5 Preview cost?

$1.1605 / $3.13335 per million tokens at the prices shown, for input and output respectively. The exact price of every call comes back in the response as usage.cost, so you never have to compute it.

### What is the context length of Step 5 Preview?

1M tokens, and it writes up to 64K tokens in one reply. These are the limits listed for this model in the current AgentSky catalog.

### Which clients can call Step 5 Preview?

Anything that speaks the OpenAI-compatible request format. Point the client's base URL at the gateway, use an AgentSky key, and pass stepfun/step-5-preview as the model.

### How do I name Step 5 Preview in a request?

The gateway accepts stepfun/step-5-preview, step-5-preview. Any of them resolves to the same model, so an existing integration usually needs no change to its model string.

### Can Step 5 Preview read images?

Yes. Its listed input types are text, image, video. Include the image with your request; image input does not imply image generation.

### What output can Step 5 Preview produce?

The listed output types are text. This model returns text. Producing image, video or audio files requires a suitable tool or another model; it is not included in text generation.

### How should I plan a long prompt for Step 5 Preview?

Plan your instructions, conversation history and source material around the 1M-token context limit, leaving room for the response. The listed response ceiling is 64K tokens. A larger window lets you supply more relevant material; it does not make unrelated content useful.

### What would 10,000 input tokens and 2,000 output tokens cost with Step 5 Preview?

At the displayed input and output rates, the model-token subtotal is $0.0178717. This example assumes uncached input and excludes additional pricing categories, tool calls and agent runtime. Actual usage determines the final charge.

### How is cached input priced for Step 5 Preview?

The catalog lists $0.11605 per million cache-read tokens. Cache writes are listed at $1.1605 per million tokens. Repeating a prompt does not by itself guarantee a cache hit; only usage reported as cached receives that rate.

### Does the Step 5 Preview token price cover an entire agent task?

No. The model price covers the model usage described above. A task can also incur tool and runtime charges, and several model calls may be needed to complete it. Compare total task usage when evaluating cost.

### How do I use Step 5 Preview on AgentSky?

This model is listed for API use. Use the model ID stepfun/step-5-preview with a supported gateway operation. The agent composer is not offered here because the current agent model menu has no compatible match.