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

# Claude Haiku 4.5

> Anthropic's smallest, fastest 4-series model. The default for production agents that have to chain dozens of LLM calls without choking on latency.

**Vendor:** Anthropic
**Model ID:** `claude-haiku-4-5`
**Capability:** 200K context · tool use · vision · prompt caching · streaming
**Pricing:** per-token, Haiku tier ([live rate](https://bytespike.ai/pricing#text))

Haiku 4.5 is the model you reach for when the *plan* is to make a lot of
LLM calls — agent loops, tool-heavy workflows, sub-LLM judges, embeddings
pipelines that need a quick rewrite step. It's not the model you ship
when one shot has to be perfect; for that use Sonnet or Opus. But its
latency floor is low enough that you can chain four or five Haiku calls
in the time Sonnet takes for one, and the quality holds for routine
classification, extraction, and routing tasks.

## Request

```bash theme={null}
curl https://llm.bytespike.ai/v1/messages \
  -H "x-api-key: $BYTESPIKE_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{
    "model": "claude-haiku-4-5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Classify this support ticket: My order is late."}
    ]
  }'
```

### Body parameters

| Field         | Type            | Required | Default           | Notes                                                  |
| ------------- | --------------- | -------- | ----------------- | ------------------------------------------------------ |
| `model`       | string          | yes      | —                 | `claude-haiku-4-5`                                     |
| `messages`    | array           | yes      | —                 | Conversation history.                                  |
| `max_tokens`  | integer         | yes      | —                 | Hard cap on response length. Max for this model: 8192. |
| `system`      | string \| array | no       | —                 | System prompt. Array form supports `cache_control`.    |
| `temperature` | number          | no       | 1.0               | Range 0.0–1.0.                                         |
| `top_p`       | number          | no       | 1.0               | Nucleus sampling.                                      |
| `tools`       | array           | no       | —                 | Supported.                                             |
| `tool_choice` | object          | no       | `{"type":"auto"}` | `auto` / `any` / `tool` (named).                       |
| `stream`      | boolean         | no       | false             | SSE streaming.                                         |

## Response

```json theme={null}
{
  "id": "msg_haiku_…",
  "type": "message",
  "role": "assistant",
  "model": "claude-haiku-4-5",
  "content": [
    {"type": "text", "text": "Logistics — delivery delay."}
  ],
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 18,
    "output_tokens": 6
  }
}
```

### Response fields

| Field                           | Type    | Notes                                                             |
| ------------------------------- | ------- | ----------------------------------------------------------------- |
| `id`                            | string  | ByteSpike-issued message ID.                                      |
| `model`                         | string  | Echoes the request `model`.                                       |
| `content`                       | array   | Text in `{"type": "text"}`; tool calls in `{"type": "tool_use"}`. |
| `stop_reason`                   | string  | `end_turn` / `max_tokens` / `tool_use` / `stop_sequence`.         |
| `usage.input_tokens`            | integer | Prompt tokens billed.                                             |
| `usage.output_tokens`           | integer | Generated tokens billed.                                          |
| `usage.cache_read_input_tokens` | integer | Present when a `cache_control` block hits.                        |

## Code examples

<CodeGroup>
  ```bash cURL theme={null}
  curl https://llm.bytespike.ai/v1/messages \
    -H "x-api-key: $BYTESPIKE_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d '{
      "model": "claude-haiku-4-5",
      "max_tokens": 1024,
      "messages": [{"role": "user", "content": "Classify this ticket: My order is late."}]
    }'
  ```

  ```python Python theme={null}
  import anthropic

  client = anthropic.Anthropic(
      base_url="https://llm.bytespike.ai/v1",
      api_key="$BYTESPIKE_API_KEY",
  )

  message = client.messages.create(
      model="claude-haiku-4-5",
      max_tokens=1024,
      messages=[
          {"role": "user", "content": "Classify this ticket: My order is late."}
      ],
  )

  print(message.content[0].text)
  ```

  ```javascript Node theme={null}
  import Anthropic from "@anthropic-ai/sdk"

  const client = new Anthropic({
    baseURL: "https://llm.bytespike.ai/v1",
    apiKey: process.env.BYTESPIKE_API_KEY,
  })

  const message = await client.messages.create({
    model: "claude-haiku-4-5",
    max_tokens: 1024,
    messages: [
      { role: "user", content: "Classify this ticket: My order is late." },
    ],
  })

  console.log(message.content[0].text)
  ```
</CodeGroup>

## Streaming

Set `"stream": true`. Response is SSE in the standard Anthropic format.
Estimated credits ship in the HTTP response before the first SSE event,
so you can short-circuit a long completion before paying for it.

## Cache control

`cache_control` blocks reduce cost on repeated prompts. Cache reads at
the discounted rate visible in the
[pricing table](https://bytespike.ai/pricing#text) under "cache read".
Cost-effective on Haiku for retrieval-heavy agent loops where the
system prompt and tool definitions are stable across calls.

```json theme={null}
{
  "model": "claude-haiku-4-5",
  "system": [
    {
      "type": "text",
      "text": "<long static system prompt>",
      "cache_control": {"type": "ephemeral"}
    }
  ],
  "messages": [...]
}
```

## Errors

| Code | Trigger                             | Billed?                  |
| ---- | ----------------------------------- | ------------------------ |
| 400  | Body validation failed              | No                       |
| 401  | Missing / revoked key               | No                       |
| 402  | Wallet exhausted                    | No                       |
| 403  | Scope denied / IP not allowlisted   | No                       |
| 422  | Param not supported (rare on Haiku) | No                       |
| 429  | Rate-limited                        | No                       |
| 5xx  | Upstream provider issue             | No (auto-retry envelope) |

See [Error Handling](/concepts/error-handling) for the full enum.

## When to use

* Production agent loops where you make 3+ LLM calls per user action.
* Routing / triage / classification ahead of a heavier model.
* Embedding pipelines that need a quick rewrite or cleanup step.
* For one-shot quality where latency is secondary, see [Sonnet 4.6](/api-reference/text/claude-sonnet-4-6).
* For long-context reasoning, see [Opus 4.7](/api-reference/text/claude-opus-4-7).

## Limits

| Limit                   | Value       |
| ----------------------- | ----------- |
| Context window          | 200K tokens |
| Max output              | 8192 tokens |
| Supports tool use       | Yes         |
| Supports vision         | Yes         |
| Supports streaming      | Yes         |
| Supports prompt caching | Yes         |