Anthropic launched Claude Haiku 5.5 (claude-haiku-5-5), its most capable model for high-volume, latency-sensitive work, with a 1M token context window, 128k max output tokens, and adaptive thinking with the effort parameter. It is available on the Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud, and Microsoft Foundry. Code written for Claude Haiku 4.5 can break: manual extended thinking (budget_tokens) returns a 400 error, adaptive thinking is on by default so responses can begin with thinking blocks, and the same text counts as more tokens.
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What to doReview the migration guide before switching existing Claude Haiku 4.5 integrations to Claude Haiku 5.5.
- Provider
- Anthropic
- Source
- platform.claude.com