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

# Fact check

> Check whether a document supports each claim in a list.

Nimble fact check takes a document and a list of claims. For each claim, it returns the probability that the document supports the claim.

Send the request to `POST /v1/systemone` with one of the fact check models:

* Put the document in `state`, as a string.
* Add one `noul` question for each claim, with the claim in `instructions`.
* The question IDs are your own. The answers use the same IDs.

## Make a request

<CodeGroup>
  ```bash curl theme={null}
  curl https://api.bespokelabs.ai/v1/systemone \
    -H "Authorization: Bearer $BESPOKE_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{
      "model": "nimble-factcheck",
      "state": "The board moved the vote to Tuesday because the CFO was travelling.",
      "questions": {
        "moved": { "type": "noul", "instructions": "The vote was moved to Tuesday." },
        "ceo": { "type": "noul", "instructions": "The CEO was travelling." }
      }
    }'
  ```

  ```python Python theme={null}
  from bespokelabs import BespokeLabs

  client = BespokeLabs()  # reads BESPOKE_API_KEY

  response = client.nimble.system_one(
      model="nimble-factcheck",
      state="The board moved the vote to Tuesday because the CFO was travelling.",
      questions={
          "moved": {"type": "noul", "instructions": "The vote was moved to Tuesday."},
          "ceo": {"type": "noul", "instructions": "The CEO was travelling."},
      },
  )
  for claim_id, answer in response.answers.items():
      print(claim_id, answer.noul)
  ```
</CodeGroup>

## Read the answer

```json theme={null}
{
  "model": "nimble-factcheck",
  "answers": {
    "moved": { "type": "noul", "noul": 0.99 },
    "ceo": { "type": "noul", "noul": 0.002 }
  },
  "usage": { "input_tokens": 25, "output_tokens": 0 },
  "request_id": "6b57f82e-6905-48a1-bc44-fe0af138d8c5"
}
```

* `noul` is the probability that the document supports every part of the claim.
* A claim counts as supported when `noul` is above 0.5. You can use a higher threshold, e.g., 0.8, when a wrong "supported" costs you more than a wrong "not supported".
* A claim that the document contradicts and a claim that the document does not mention are both not supported.

## Models

| Model | How it answers |
| - | - |
| `nimble-factcheck-lite` | A small model scores every claim. This is the fastest and the cheapest. |
| `nimble-factcheck` | The small model scores every claim. Then a larger model scores again the claims that the small model is unsure about. This is about one claim in five. |
| `nimble-factcheck-max` | The small model scores every claim. Then two of the largest models score again the claims that the small model is unsure about, and Nimble uses the average of their scores. This is the most accurate. |

The largest models of `nimble-factcheck-max` are running on weekdays from 07:30 to 19:00 Pacific time. At other times, a request that needs those models gets `503` with a `Retry-After` header while the models start. Starting takes from about 5 to 20 minutes. You are not charged for a `503`.

## Options

`split_claims` is `true` by default. Nimble then scores each sentence of a claim on its own and keeps the lowest score. Set it to `false` to score each claim whole. Put it at the top level of the request, next to `model`.

```json theme={null}
{
  "model": "nimble-factcheck",
  "split_claims": false,
  "state": "The board moved the vote to Tuesday because the CFO was travelling.",
  "questions": {
    "moved": { "type": "noul", "instructions": "The vote was moved to Tuesday because the CFO was travelling." }
  }
}
```

## Limits

| Limit | Value |
| - | - |
| Claims in a request | 1 to 64 |
| Characters in one claim | 4,000 |
| Characters in the document | 400,000 |

The questions must be `noul` questions with no `criteria`. Any other question gets `422`.

Nimble splits a long document into parts. A sentence counts as supported if any part supports it.