migration-guide changedmodels/haiku-5-5/migration-guide
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119119## Remove sampling parameters
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121Claude Haiku 4.5 accepts `temperature`, `top_p`, and `top_k`. On Claude Haiku 5.5, omit all three and use prompting to guide the model's behavior instead. If a request includes `temperature`, it must be `1`. If it includes `top_p`, it must be `0.99`, its default. Any other `temperature` or `top_p` value returns a 400 error, including a `top_p` of `1`. So does any `top_k` value, and so does a request that includes both `temperature` and `top_p`.
121On Claude Haiku 5.5, omit `temperature`, `top_p`, and `top_k` and use prompting to guide the model's behavior instead.
122122
123123## Replace assistant prefill
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