# Anthropic Models

Instructions for using language models hosted on Anthropic with Spice.

To use a language model hosted on Anthropic, specify `anthropic` in the `from` field.

To use a specific model, include its model ID in the `from` field (see example below). If not specified, the default model is `claude-sonnet-4-6`. Name a model explicitly for anything long-lived: Anthropic retires model IDs, and a request for a retired one fails with a `not_found_error`.

The default deliberately trails Anthropic's newest model. Claude 5 models reject `temperature` and `top_p` individually, so a request that sets either of them fails against them; `claude-sonnet-4-6` is the newest model that still accepts each of them. It accepts them one at a time, not in every combination: Claude 4 and later reject `temperature` and `top_p` set _together_, and reject a trailing assistant message (a response prefill). Set `from: anthropic:<model_id>` to use a newer model, and drop these parameters when you do.

When a model refuses `temperature` or `top_p`, Spice returns HTTP `400` with an error that names the model, the parameter, and where to remove it:

```
Failed to run a chat completion with Anthropic model 'claude-sonnet-5': the model does not accept the `temperature` parameter. Remove `temperature` from the request and from the model's `params` (as `temperature`, `anthropic_temperature` or `openai_temperature`), or set `from: anthropic:<model_id>` to a model that accepts it. Cause: `temperature` is deprecated for this model. See: https://spiceai.org/docs/components/models/anthropic
```

A streaming request receives the same message in an SSE `error` event.

Per-token log probabilities are not available from any Anthropic model: the Messages API returns none. A request that sets `logprobs: true` or `top_logprobs` is therefore refused by Spice before it reaches Anthropic, rather than answered with a completion that silently omits what was asked for. The refusal is an `invalid_request_error` naming the parameter:

```
Failed to run model 'claude-sonnet-4-6' (anthropic): the `top_logprobs` parameter is not supported. Anthropic's Messages API returns no per-token log probabilities. Remove `top_logprobs` from the request and from the model's parameters, or use a model provider that reports them. See: https://spiceai.org/docs/components/models/anthropic
```

Either field can arrive from the request or from the model's [parameter overrides](https://spiceai.org/docs/features/large-language-models/parameter_overrides), so remove it from both. `logprobs: false` asks for nothing and is accepted.

The following parameters are specific to Anthropic models:

| Parameter | Description | Default |
| - | - | - |
| `anthropic_api_key` | The Anthropic API key. | - |
| `anthropic_auth_token` | The Anthropic Auth Token. | - |
| `anthropic_workspace_id` | The Anthropic workspace ID, sent as the `anthropic-workspace-id` header. Required when the API key is not scoped to a workspace. | - |
| `anthropic_usage_tier` | Anthropic usage tier (1-4). Used for rate limit defaults. | - |
| `endpoint` | The Anthropic API base endpoint. | `https://api.anthropic.com/v1` |

Example `spicepod.yml` configuration:

```yaml
models:
  - from: anthropic:claude-sonnet-4-5
    name: claude_4_5_sonnet
    params:
      anthropic_api_key: ${ secrets:SPICE_ANTHROPIC_API_KEY }
```

An API key that is not scoped to a single workspace needs `anthropic_workspace_id`, because Anthropic runs a request from a multi-workspace key in the workspace named by its `anthropic-workspace-id` header (see [API keys and resource scoping](https://platform.claude.com/docs/en/manage-claude/workspaces#api-keys-and-resource-scoping)). When the parameter is set, Spice sends the header on chat requests and on the request that lists available models. A value that is not a valid HTTP header value fails the model load with an error that begins `` Invalid `anthropic_workspace_id` ``.

```yaml
models:
  - from: anthropic:claude-sonnet-4-6
    name: anthropic
    params:
      anthropic_api_key: ${ secrets:SPICE_ANTHROPIC_API_KEY }
      anthropic_workspace_id: wrkspc_...
```

See [Anthropic Model Names](https://platform.claude.com/docs/en/about-claude/models/overview) for a list of supported model names.