What actually happened

Anthropic released Claude Haiku 5.5 on 7 October 2026. It is the cheapest, fastest, and most capable small model the company has shipped, and the first Haiku with an adjustable effort setting. Adaptive thinking is on by default. Effort defaults to medium.

The context window is 1 million tokens, with up to 128K output. List price for prompts up to 100K tokens is $0.10 per million input and $0.50 per million output. Cache reads are $0.01 and 5-minute cache writes are $0.125. Above 100K, those rates rise to $0.50 input and $2.50 output. Anthropic says about 90% of prior Haiku requests sat under that line, and that the short-prompt list price is 90% below Haiku 4.5. The average saving they quote is about 75%, because the new tokenizer counts roughly 30% more tokens on the same text.

The model is generally available on the Claude API, Amazon Bedrock, Google Cloud, Microsoft Foundry, and Claude Platform on AWS. Model ID is claude-haiku-5-5. The same launch halves Sonnet 5.5 cache-read prices, which Anthropic says makes Sonnet about 20% cheaper on most agentic work.

Why a small team cares

A two-person product shop that fans a ticket into a classifier, an extractor, and a short subagent used to pay Haiku 4.5 rates of $1 / $5 per million, or burn Sonnet on steps that did not need it. At $0.10 / $0.50 under 100K, the same fan-out can run on every inbound lead instead of a sample. Effort control is the practical extra: medium for the bulk route, higher only where the miss rate shows up. You do not have to pick a dumber model to get the bill down.

Hype vs useful

The useful part is the routing bill, not a claim that Haiku replaces Sonnet. Anthropic's own charts put some scores at maximum effort. Medium is the default, and it will not match a max-effort demo. Skip temperature, top_p, and top_k. A non-default value returns a 400. Judge the switch on one route you already run, with the tokenizer bump in the cost sheet, and keep the larger model on the step a client would notice.

Source: anthropic.com (https://www.anthropic.com/claude-haiku-5-5)