Anthropic ships Haiku 5.5 through Claude API and cloud platforms

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Haiku 5.5 is now available through the Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud, and Microsoft Foundry. The release also adds beta dynamic workflows to Claude Managed Agents.

Here's what changed:

• Context reaches 1M tokens, with up to 128k output tokens.
• Adaptive thinking is enabled by default and supports the effort parameter. Set thinking.display to "summarized" to receive thinking text, which uses additional tokens.
• Managed Agents can create workflows for multi-part work. The server runs multiple agents in phases, combines their results, and emits workflow_run.* events.

One catch: Haiku 4.5 requests using manual extended thinking with budget_tokens, sampling parameters, assistant-message prefill, or computer_20250124 can return 400 errors. Use the replacement computer toolset for your platform. Structured outputs are unavailable on Bedrock.

Try it: Use claude-haiku-5-5 in a Claude API request.

Sources: platform.claude.com