> The full index of these docs is at [llms.txt](https://u22a8.ai/llms.txt).

# When to use A8

The judgments A8 is built for, the tools that fit the other jobs and when A8 pays off.

A8 is built for one job: deciding whether a subject meets a criterion, at the minimum accuracy you set. It returns a **verdict**: a label, a number or a JSON object. Where its evidence falls short of the minimum accuracy, it abstains. For writing text, use a generative model, and use A8 to check what it wrote.

## 1 What A8 is for

A8 judges text against a criterion stated in plain words. Each request asks one question about one subject, and the answer is a verdict in the shape you give:

- **A label:** true or false, or one of several categories, such as the queue a ticket belongs in.
- **A score:** a number on a declared scale, such as how polite a reply is from 1 to 5.
- **A JSON object:** several fields at once, each judged as its own criterion.

Every verdict carries the level it is promised at, and the same request returns the same verdict.

## 2 Match the job to the tool

| You want to…                                              | Do this                                                                                                                                                                                                                                                                                                       |
| --------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Write, rewrite, translate or summarize text               | Use a generative model                                                                                                                                                                                                                                                                                        |
| Decide whether a reply meets a criterion                  | Call A8 with the criterion as the system message                                                                                                                                                                                                                                                              |
| Route a ticket or a document to one of several categories | Call A8 with an `enum` in the schema                                                                                                                                                                                                                                                                          |
| Score a reply on a scale                                  | Call A8 with a `number` or `integer` property                                                                                                                                                                                                                                                                 |
| Hold an answer against a reference answer or a policy     | Call A8 with `reference` in the subject                                                                                                                                                                                                                                                                       |
| Grade the outputs of an LLM app in promptfoo or Inspect   | Point the tool at A8; see [promptfoo](https://u22a8.ai/docs/promptfoo.md) and [Inspect](https://u22a8.ai/docs/inspect.md)                                                                                                                                                                                     |
| Gate a release on the same verdicts every run             | Pin an A8 version; see [Horizons](https://u22a8.ai/docs/a8-horizons.md)                                                                                                                                                                                                                                       |
| Show the reasons behind a verdict                         | Ask A8 for [precedents](https://u22a8.ai/docs/a8-precedents.md): the taught examples that decided it                                                                                                                                                                                                          |
| Judge an image or audio                                   | Use a model that reads images or audio. A8 reads text                                                                                                                                                                                                                                                         |
| Move a prompt written for an LLM judge                    | Send it to A8 as it is; see the page for your tool: [OpenAI SDK](https://u22a8.ai/docs/openai-sdk.md), [Anthropic SDK](https://u22a8.ai/docs/anthropic-sdk.md), [promptfoo](https://u22a8.ai/docs/promptfoo.md), [Inspect](https://u22a8.ai/docs/inspect.md) or [DeepEval](https://u22a8.ai/docs/deepeval.md) |

*Table 1.* Each job beside the tool that does it; A8 covers the rows that end in a verdict.

## 3 When A8 pays off

- **The same criterion runs over many subjects.** A criterion you state once judges every ticket, reply or document that follows, and teaching it improves every later verdict.
- **A wrong verdict has a cost.** You set the minimum accuracy each call must meet. A8 answers where its evidence meets it, and a person takes the cases it abstains on. See [Send abstentions to a person](https://u22a8.ai/docs/send-abstentions-to-a-person.md).
- **The verdict has to repeat.** Audits, regression suites and release gates need the same answer for the same request. A pinned version returns the same verdict while its `system_fingerprint` holds.
- **The criterion is yours.** House conventions and policies the reference model has yet to see are taught one example at a time, from inside a conversation. See [Teaching](https://u22a8.ai/docs/a8-teaching.md).

A one-off question, or a judgment that needs a written argument as its answer, suits a generative model.

## Next steps

- [Quickstart: a first verdict](https://u22a8.ai/docs/quickstart.md): Get a key, call A8 from an SDK, from curl or from your assistant, and read the verdict it returns.
- [Write a criterion](https://u22a8.ai/docs/writing-criteria.md): State a criterion A8 judges well, with one judgment per criterion, the situation that decides it and the practices that keep verdicts steady.
- [A8 model card](https://u22a8.ai/docs/a8.md): A8 on one page: model IDs, pricing, capabilities, endpoints, features, rate limits and how it compares.