# Claude family API: model IDs, choosing an endpoint, examples and common errors

Source: https://ofox.ai/docs/develop/models/claude

Anthropic's Claude models, including the Opus, Sonnet, Haiku and Fable series. We recommend calling them through the **Anthropic-native API**, where extended thinking, prompt caching, PDF input and other features behave as in the official API. The OpenAI-compatible API also works and suits projects that already use the OpenAI SDK.

## Common tasks

- [Enable extended thinking](https://ofox.ai/docs/develop/models/claude/thinking) — thinking, budget_tokens, adaptive, and how to read the thinking content.
- [Prompt caching](https://ofox.ai/docs/develop/models/claude/caching) — cache_control, 1-hour caching, and how to confirm a cache hit.
- [Web search](https://ofox.ai/docs/develop/models/claude/web-search) — The web_search tool; requires the Anthropic provider.
- [Long context & PDF](https://ofox.ai/docs/develop/models/claude/pdf) — 1M context and PDF uploads.
- [Troubleshooting errors](#errors) — prompt is too long, model not found, truncated responses.
- [Use in Claude Code](https://ofox.ai/docs/integrations/claude-code) — Setup and common questions.

## Models
All models accept text, image and PDF input and support tool calling. For the full model list and live prices, see the [model page](https://ofox.ai/models?provider=anthropic), or query the [Models API](https://ofox.ai/docs/api/openai/models).

**Common model IDs (copy them exactly)**

- Claude Opus 5.5: `anthropic/claude-opus-5.5`
- Claude Sonnet 5.5: `anthropic/claude-sonnet-5.5`
- Claude Haiku 5.5: `anthropic/claude-haiku-5.5`
- Claude Fable 5.1: `anthropic/claude-fable-5.1`

You can omit the `anthropic/` prefix or use Anthropic's official format. All of the following refer to the same model:

| Format | Example |
|---|---|
| OfoxAI standard | `anthropic/claude-sonnet-4.6` |
| Prefix omitted | `claude-sonnet-4.6` |
| Official (hyphens) | `claude-sonnet-4-6` |
| Official with date | `claude-sonnet-4-6-20260217` |

The aliases available for each model are listed in the `aliases` field returned by the Models API. The `model` field in responses always uses the standard format.

## Choosing an endpoint

**Key point**:Use the Anthropic-native API for extended thinking, prompt caching, or tools such as Claude Code.

| | Anthropic-native API (recommended) | OpenAI-compatible API |
|---|---|---|
| Endpoint | `POST https://api.ofox.ai/anthropic/v1/messages` | `POST https://api.ofox.ai/v1/chat/completions` |
| SDK `base_url` | `https://api.ofox.ai/anthropic` | `https://api.ofox.ai/v1` |
| Authentication | `x-api-key: <Key>`; `Authorization: Bearer <Key>` is also accepted | `Authorization: Bearer <Key>` |
| [Extended thinking](https://ofox.ai/docs/develop/models/claude/thinking) | `thinking` parameter; returns `thinking` blocks | `reasoning` parameter; returns `reasoning_details` |
| [Prompt caching](https://ofox.ai/docs/develop/models/claude/caching) | `cache_control`; usage reports both cache writes and reads | Add `cache_control` to message content blocks; usage reports reads only |
| [PDF](https://ofox.ai/docs/develop/models/claude/pdf) | `document` content block | `file` content block |
| [Web search](https://ofox.ai/docs/develop/models/claude/web-search) | Supported (requires the Anthropic provider) | Not supported |

For the full request parameters, see the [Anthropic Messages API](https://ofox.ai/docs/api/anthropic/messages) and the [Chat Completions API](https://ofox.ai/docs/api/openai/chat-completions).

### Providers
Claude models are served by two providers, and the same model supports different features on each:

| Provider | Models | Endpoints | Notes |
|---|---|---|---|
| Amazon Bedrock (`aws_bedrock`) | All models | Both | Default provider |
| Anthropic (`anthropic`) | Fable 5, Opus 4.8, Opus 4.7, Sonnet 5 | Anthropic-native API only | Supports [web search](https://ofox.ai/docs/develop/models/claude/web-search); must be selected explicitly |

On the Anthropic-native API, you can select the provider with a request header:

```bash
-H "X-OfoxAI-Provider-Type: anthropic"
```

If the selected provider doesn't serve the model, the request returns 400 and the error message lists the available providers, for example:

```text
No available channel for platform 'anthropic' on model 'anthropic/claude-sonnet-4.6'. Available platforms for this model: aws_bedrock.
```

For other ways to select a provider, see [Provider routing](https://ofox.ai/docs/develop/advanced/provider-routing).

## Examples

**Python (Anthropic SDK)**

```python filename="claude_basic.py"
import os
import anthropic

client = anthropic.Anthropic(
    base_url="https://api.ofox.ai/anthropic",
    api_key=os.environ["OFOX_API_KEY"],
)

message = client.messages.create(
    model="anthropic/claude-sonnet-4.6",
    max_tokens=1024,
    system="You are a senior backend engineer. Keep answers concise.",
    messages=[{"role": "user", "content": "Explain idempotency in one sentence."}],
)
print(message.content[0].text)
```

**cURL**

```bash filename="Terminal"
curl https://api.ofox.ai/anthropic/v1/messages \
  -H "x-api-key: $OFOX_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-sonnet-4.6",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "Explain idempotency in one sentence."}]
  }'
```

**Python (OpenAI SDK)**

```python filename="claude_openai_sdk.py"
import os
from openai import OpenAI

client = OpenAI(base_url="https://api.ofox.ai/v1", api_key=os.environ["OFOX_API_KEY"])

resp = client.chat.completions.create(
    model="anthropic/claude-sonnet-4.6",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Explain idempotency in one sentence."}],
)
print(resp.choices[0].message.content)
```

`max_tokens` is required on the Anthropic-native API and must not exceed the model's maximum output.

## Use in Claude Code
Claude Code calls the Anthropic-native API, with the base URL `https://api.ofox.ai/anthropic`. For setup steps, see [Claude Code setup](https://ofox.ai/docs/integrations/claude-code).

**Claude Code settings**

- ANTHROPIC_BASE_URL: `https://api.ofox.ai/anthropic`
- ANTHROPIC_AUTH_TOKEN: Paste your OfoxAI API key

## Common errors

**Key point**:Parameter errors return 400 with a reason. A truncated response is not an error; check stop_reason.

| HTTP · type | Error message | Cause | Fix |
|---|---|---|---|
| 400 `ValidationException` | `prompt is too long: 280527 tokens > 200000 maximum` | Input exceeds the model's context window | Shorten the input, or switch to a model with 1M context (any model other than Haiku 4.5) |
| 404 `model_not_found` | `Model 'anthropic/claude-sonnet-9' not found` | Model ID misspelled, or the model has been retired | Copy the model ID from this page |
| 401 `invalid_api_key` | `Invalid or expired API key` | Key is wrong, deleted or expired | Check the key in the console; on the native API, check the `x-api-key` header |
| 400 | `No available channel for platform 'anthropic' on model ...` | The selected provider doesn't serve this model | Remove the provider selection, or use a provider listed in the error message — see [Providers](#provider) |
| 200, `stop_reason: "max_tokens"` | — | Output reached the `max_tokens` limit and the response was truncated | Increase `max_tokens`; with thinking enabled, thinking also counts against this limit |

For other general errors, see [Error Handling](https://ofox.ai/docs/develop/guides/error-handling).

## Official docs
- [Anthropic · Models overview](https://docs.anthropic.com/en/docs/about-claude/models/overview)
- [Anthropic · Extended thinking](https://docs.anthropic.com/en/docs/build-with-claude/extended-thinking)
- [Anthropic · Prompt caching](https://docs.anthropic.com/en/docs/build-with-claude/prompt-caching)
- [Anthropic · PDF support](https://docs.anthropic.com/en/docs/build-with-claude/pdf-support)

The official docs describe behavior when calling Anthropic directly. When calling through OfoxAI, model IDs and endpoints on this page take precedence.

## FAQ

**How do I write a Claude model ID?**

The standard format is anthropic/claude-sonnet-4.6. You can also omit the anthropic/ prefix, or use the official formats claude-sonnet-4-6 and claude-sonnet-4-6-20260217; all refer to the same model.

**Can I call Claude with the OpenAI SDK?**

Yes. Set base_url to https://api.ofox.ai/v1 and use a model ID such as anthropic/claude-sonnet-4.6. If you need extended thinking or full cache usage details, we recommend the Anthropic-native API.

**How do I enable thinking for Claude?**

On the native API, pass thinking: {"type": "enabled", "budget_tokens": 2000}, where budget_tokens is at least 1024 and less than max_tokens; or pass {"type": "adaptive"} to let the model decide. On the OpenAI-compatible API, pass reasoning: {"max_tokens": 2000}. Do not set temperature when thinking is enabled.

**What should I do if Claude prompt caching is not working?**

Check in order: whether cache_control is set on the fixed content blocks (neither endpoint caches automatically); whether the content reaches the minimum cacheable length; whether the prefixes of the two requests are exactly identical; and whether more than 5 minutes passed between the two requests.

**How do I fix the error prompt is too long?**

The input exceeds the model context window. Haiku 4.5 has a 200K-token context; other Claude models have 1M tokens. Switch to another model or shorten the input.

**Does Claude support 1M context? Do I need a beta header?**

All models except Haiku 4.5 support 1M context. On OfoxAI no beta header is needed.

**What should I do if Claude responses are truncated?**

Check stop_reason in the response. If it is max_tokens, the output hit the limit; increase max_tokens. With thinking enabled, thinking content also counts against max_tokens.

**Which provider serves Claude on OfoxAI?**

All models are served by Amazon Bedrock, the default provider. Fable 5, Opus 4.8, Opus 4.7 and Sonnet 5 are also available from the Anthropic provider, on the Anthropic-native API only; select it with the X-OfoxAI-Provider-Type: anthropic header.

**Can Claude search the web?**

Yes, but it requires the Anthropic provider, is limited to Fable 5, Opus 4.8, Opus 4.7 and Sonnet 5, and works only on the Anthropic-native API. Add {"type": "web_search_20250305", "name": "web_search"} to tools.

**Can Claude read PDFs?**

Yes. On the native API, pass a base64-encoded PDF in a document content block; on the OpenAI-compatible API, use a file content block with file_data in the data:application/pdf;base64,... format.