OpenAIAnthropicGooglexAIPerplexity
← Back to all updatesPublished ·Anthropic• Minor
Non-default `temperature`, `top_p`, or `top_k` returns a 400 error on Claude Opus 4.8.
The read
Custom sampling parameters now fail on Claude Opus 4.8, making default sampling the safe path.
The frame
This matches Claude Opus 4.7 behavior, so integrations carrying custom sampling parameters need migration-guide handling.
Primary source
Anthropic →Keep reading
See what Nova3 builds →Related updates
- Jun 12, 2026Anthropic publicly documented stop_details on refusal responses, with category and explanation fields for routing.
- Jun 12, 2026Claude Opus 4.8 defaults the effort parameter to high across all surfaces.
- Jun 12, 2026Claude Opus 4.8 lowers prompt caching’s minimum cacheable prompt length to 1,024 tokens versus Opus 4.7.
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