---
title: "Make decisions with the decision API"
canonical_url: "https://www.nutrient.io/guides/dws-ai-gateway/system-one/"
md_url: "https://www.nutrient.io/guides/dws-ai-gateway/system-one.md"
last_updated: "2026-10-14T00:00:00.000Z"
description: "Use the AI Gateway decision API for yes/no, choice, and score questions with probabilities."
---

# Make decisions with the decision API

Use the decision API to ask structured questions about content and receive probabilities for yes/no answers, choices, or scores. The current endpoint is `/systemone`, with the model alias `nutrient-systemone`.

## Prerequisites

Complete [getting started](https://www.nutrient.io/guides/dws-ai-gateway/getting-started.md) and confirm that `nutrient-systemone` appears in the `models` array from [model discovery](https://www.nutrient.io/api/reference/ai-gateway/public/). The decision API requires account access in addition to AI Gateway access.

## Ask a yes/no question

Send the content to evaluate in `state`, and name each question in `questions`:

```shell

curl --fail-with-body https://api.nutrient.io/ai/v1/systemone \
  -H "Authorization: Bearer $NUTRIENT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "nutrient-systemone",
    "state": "I was charged twice for my subscription this month.",
    "questions": {
      "billing": {
        "type": "noul",
        "instructions": "Is this message about billing?"
      }
    }
  }'

```

Read `answers.billing.noul` as a probability from 0 to 1 that the answer is yes. It is not a Boolean. Choose decision thresholds using your own evaluation data, and route uncertain results for review.

## Question formats

Use `noul` for yes/no questions, `choice` to pick one label, and `score` to place the content on an ordered scale. See the [API reference](https://www.nutrient.io/api/reference/ai-gateway/public/) for each format, the limits for each model, and request size limits.

## Billing and request IDs

The decision API uses AI Gateway token billing. See the [dashboard pricing page](https://dashboard.nutrient.io/ai-gateway/pricing/) for current rates, or discover account-specific rates with a live key.

## Next steps

- [Pricing](https://www.nutrient.io/guides/dws-ai-gateway/pricing.md) — Understand token billing.

- [Errors and limits](https://www.nutrient.io/guides/dws-ai-gateway/errors.md) — Handle rejected requests and unavailable access.
---

## Related pages

- [DWS AI Gateway API](/guides/dws-ai-gateway.md)
- [AI Gateway errors and limits](/guides/dws-ai-gateway/errors.md)
- [Get started with DWS AI Gateway API](/guides/dws-ai-gateway/getting-started.md)
- [AI Gateway pricing](/guides/dws-ai-gateway/pricing.md)
- [AI Gateway security and privacy](/guides/dws-ai-gateway/security-and-privacy.md)