Claude Haiku 5.5 - AnyFast

Claude Haiku 5.5 is Anthropic’s fast model for high-volume, latency-sensitive work. Call it through AnyFast’s Anthropic Messages API at POST /v1/messages using the model ID claude-haiku-5-5.

Key capabilities

1M context window — Supports up to 1M context tokens and 128K output tokens according to Anthropic’s model specification
Adaptive thinking — On by default; use output_config.effort to balance speed and depth
Fast routine work — Suited to classification, extraction, routing, and high-volume assistants
Tool use and vision — Accepts text and image inputs and can return text or tool calls
Model ID — Use claude-haiku-5-5 in requests

Quick example

curl https://www.anyfast.ai/v1/messages \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-haiku-5-5",
    "max_tokens": 1024,
    "output_config": {"effort": "low"},
    "messages": [
      {"role": "user", "content": "Classify this ticket as billing, technical, or account: I cannot reset my password."}
    ]
  }'

import anthropic

client = anthropic.Anthropic(
    api_key="YOUR_API_KEY",
    base_url="https://www.anyfast.ai",
)

message = client.messages.create(
    model="claude-haiku-5-5",
    max_tokens=1024,
    output_config={"effort": "low"},
    messages=[{"role": "user", "content": "Extract the due date from: Pay by Friday."}],
)

for block in message.content:
    if block.type == "text":
        print(block.text)

import anthropic

client = anthropic.Anthropic(
    api_key="YOUR_API_KEY",
    base_url="https://www.anyfast.ai",
)

with client.messages.stream(
    model="claude-haiku-5-5",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Summarize this support ticket."}],
) as stream:
    for text in stream.text_stream:
        print(text, end="")

Parameters

Parameter	Type	Required	Description
`model`	string	Yes	Must be `claude-haiku-5-5`.
`messages`	array	Yes	User and assistant turns with text, image, or tool-result content.
`max_tokens`	integer	Yes	Maximum output tokens across thinking and visible text; up to 128,000.
`output_config`	object	No	Set `effort` to `low`, `medium`, `high`, `xhigh`, or `max`; default `medium`.
`thinking`	object	No	Adaptive by default. To disable thinking, omit `output_config.effort` and use `{"type":"disabled"}`.
`tools`	array	No	Tool definitions.
`tool_choice`	object	No	Use `auto`, `none`, `any`, or a named `tool`.
`stream`	boolean	No	Enable SSE streaming; default `false`.

On AnyFast, thinking: {"type":"disabled"} succeeded when output_config.effort was omitted; combining it with explicit effort: "low" returned 400. Forced tool_choice: {"type":"any"} succeeded and produced a tool_use block. Omit custom temperature, top_p, and top_k values, and read response content blocks by type.

In a tested AnyFast text response, the request ID claude-haiku-5-5 appeared as model: "claude-haiku-5.5". The response also included request_id, billing.billed_cost_usd as a string, and usage.service_tier. Keep using the hyphen-form ID in requests.

API Reference

Review the Claude Haiku 5.5 request and response fields.