Per-Model Details
How specific model families handle parameters differently from the defaults in Parameter Support by Model. All parameters below are top-level request fields unless noted — you can send them through any API format. The router normalises them automatically, so you generally don't need to know these details; they're here for when you want precise control.
GPT-5 series
GPT-5 models apply strict parameter sanitisation:
| Parameter | Behaviour |
|---|---|
max_tokens |
Automatically converted to max_completion_tokens. |
temperature |
Accepted only when = 1.0, or when reasoning_effort = "none" (GPT-5.1+). |
presence_penalty, frequency_penalty, stop, logit_bias |
Always dropped. |
logprobs, top_logprobs, top_p |
Accepted only when reasoning_effort = "none" (GPT-5.1+). |
reasoning_effort |
Supported on all GPT-5 variants. |
Claude 4+
The router normalises the thinking parameter to match the target Claude model — clients
don't need to know which mode a model uses.
Adaptive thinking models (Claude Sonnet 4.6, Opus 4.6, Opus 4.7, Opus 4.8 and newer):
| Parameter | Behaviour |
|---|---|
thinking.type = "enabled" |
Converted to "adaptive". budget_tokens is optional and ignored when adaptive. |
thinking.type = "adaptive" |
Passed through directly. |
reasoning_effort |
Mapped to thinking.type = "adaptive". |
Non-adaptive thinking models (Claude Haiku 4.5, Sonnet 4.5, Opus 4.5):
| Parameter | Behaviour |
|---|---|
thinking.type = "enabled" |
Requires budget_tokens (minimum 1024). |
thinking.type = "adaptive" |
Converted to "enabled" with a default budget. |
reasoning_effort |
Mapped to budget_tokens (low / medium / high → token counts). |
budget_tokens |
Must be ≥ 1024 and less than max_tokens. |
All Claude models support tools, tool_choice, parallel_tool_calls, temperature,
top_p, max_tokens, and response_format.
Gemini
| Parameter | Behaviour |
|---|---|
thinking / reasoning_effort |
Accepted on all Gemini models; silently ignored on models without thinking support. |
frequency_penalty, presence_penalty |
Not available on preview or Gemini 3 models. |
top_k |
Not a standard top-level field — pass via extra_body; forwarded when supported natively. |