AI EngineerGuide

temperature, top_p and top_k can return an error on Claude Haiku 5.5

Can return an error Applies to claude-haiku-5-5 on the Anthropic Messages API.

Anthropic's docs describe this error but don't quote the exact message, so we don't either.

How to fix it

Omit temperature, top_p and top_k, and use prompting to guide the model’s behavior.

Before
{
  "max_tokens": 1024,
  "messages": [
    {
      "content": "Summarize this ticket.",
      "role": "user"
    }
  ],
  "model": "claude-haiku-4-5-20251001",
  "top_p": 0.9
}
After (Claude Haiku 5.5)
{
  "max_tokens": 1024,
  "messages": [
    {
      "content": "Summarize this ticket.",
      "role": "user"
    }
  ],
  "model": "claude-haiku-5-5"
}
Check your whole request in the linter

Official source

omit temperature, top_p, and top_k and use prompting to guide the model’s behavior instead.

https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide (last checked 2026-11-02)

Other changes for the same models

All migration errors

FAQ

How do I fix this when moving to claude-haiku-5-5?

Omit temperature, top_p and top_k, and use prompting to guide the model’s behavior.

Where is this documented?

In Anthropic’s official docs: https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide, last checked 2026-11-02.