migration-guide changedmodels/haiku-5-5/migration-guide
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28284. If your code reads the first content block as the answer, select blocks by `type` instead. See [Configure thinking](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#configure-thinking).
29295. Remove `temperature`, `top_p`, and `top_k` from your requests. See [Remove sampling parameters](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#remove-sampling-parameters).
30306. If your requests end `messages` with an assistant turn for the model to continue, end them with a user turn instead. See [Replace assistant prefill](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#replace-assistant-prefill).
317. If you use computer use, replace `computer_20250124`: on the Claude API and Claude Models on Google Cloud (Google managed), with the `computer_toolset_20260801` toolset; on Amazon Bedrock, with `computer_20251124` and the `computer-use-2025-11-24` beta header. See [Move computer use to the toolset](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#computer-use-toolset).
317. If you use computer use, replace `computer_20250124` with the `computer_toolset_20260801` toolset. On Amazon Bedrock, `computer_20251124` also works. See [Move computer use to the toolset](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#computer-use-toolset).
32328. If you replay stored conversations through a different account, replay each one through the account that produced it. See [Replay thinking blocks through the account that produced them](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#replay-thinking-blocks-through-the-producing-account).
33339. If your code changes `system`, `tools`, or earlier `messages` between requests in a conversation and sends thinking blocks back, keep the conversation append-only. See [Keep earlier turns unchanged](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#keep-earlier-turns-unchanged).
343410. Handle `stop_reason: "refusal"`. Claude Haiku 5.5 runs safety classifiers that can decline a request, and it has no server-side fallback. See [Safeguard refusals](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-haiku-5-5#safeguard-refusals).
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126126
127127## Move computer use to the toolset
128128
129Claude Haiku 4.5 supports [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) through the `computer_20250124` tool, with the `computer-use-2025-01-24` beta header. On the Claude API and Claude Models on Google Cloud (Google managed), Claude Haiku 5.5 supports computer use only through the `computer_toolset_20260801` toolset, and a request that declares `computer_20250124` returns a 400 error. On Amazon Bedrock, Claude Haiku 5.5 doesn’t accept `computer_20250124` either; use the `computer_20251124` tool version with the `computer-use-2025-11-24` beta header.
129Claude Haiku 4.5 supports [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) through the `computer_20250124` tool, with the `computer-use-2025-01-24` beta header. Claude Haiku 5.5 supports computer use through the `computer_toolset_20260801` toolset. A request to Claude Haiku 5.5 that declares `computer_20250124` returns a 400 error.
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131To move an integration to the toolset, drop the `computer-use-2025-01-24` beta header and replace the `tools` entry with `{"type": "computer_toolset_20260801"}`. Then make the other request and agent-loop changes in [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124): dispatch on each member `tool_use` block’s `name` and `toolset_name` rather than on `input.action`, handle every such block in a turn, and echo `toolset_name` on results. Zoom is on by default in the toolset; if your environment doesn’t implement it, add `"configs": {"zoom": {"enabled": false}}`. If you send the `fine-grained-tool-streaming-2025-05-14` beta header, remove it. Alongside a toolset entry, it returns a 400 error. For other platforms, see the computer use tool’s [API support](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#availability-feature-support) section.
131To move an integration to the toolset, drop the `computer-use-2025-01-24` beta header and replace the `tools` entry with `{"type": "computer_toolset_20260801"}`. Then make the other request and agent-loop changes in [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124). Dispatch on each member `tool_use` block’s `name` and `toolset_name` rather than on `input.action`. Handle every such block in a turn and echo `toolset_name` on results. Zoom is on by default in the toolset; if your environment doesn’t implement it, add `"configs": {"zoom": {"enabled": false}}`. If you send the `fine-grained-tool-streaming-2025-05-14` beta header, remove it. Alongside a toolset entry, it returns a 400 error.
132132
133On the Claude API and Claude Models on Google Cloud (Google managed), Claude Haiku 5.5 also supports the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) (`browser_toolset_20260801`) for tasks inside webpages. Claude Haiku 4.5 doesn’t support it.
133On Amazon Bedrock, Claude Haiku 5.5 also accepts the `computer_20251124` tool with the `computer-use-2025-11-24` beta header.
134
135Claude Haiku 5.5 supports the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) (`browser_toolset_20260801`) for tasks inside webpages. Claude Haiku 4.5 doesn’t support it.
134136
135137## Replay thinking blocks through the account that produced them
136138
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