Google's prompting-strategies page explicitly says that Gemini 4, including Gemini 4 Argon currently shown as available on the page, ignores custom temperature, top_p, and top_k values in requests. The current behavior returns a deprecation-warning header; future versions will return 400, so Argon request configurations should remove these three parameters.
Suitable tasks: Reviewing Gemini 4 Argon request configurations, removing sampling parameters that no longer take effect, and focusing prompt-quality controls on clear instructions, constraints, output formats, and few-shot examples.
Unsuitable tasks: Configurations that need to control Argon's output randomness by adjusting temperature, top_p, or top_k; the page explicitly says these custom values are ignored.
Model version: gemini-4-argon; the original states the parameter restriction as a Gemini 4 rule, and the page also shows “Gemini 4 Argon is now available.”
Client, Agent, or API: Gemini API request configuration; the page does not provide Argon-specific SDK request code or a complete schema.
Recommended reasoning tier and parameters: Remove temperature, top_p, and top_k; make the task, constraints, and output format explicit in the prompt. The page does not specify a reasoning tier or replacement sampling parameters for Argon here.
Fix the model as gemini-4-argon.
Remove temperature, top_p, and top_k from the request configuration.
Do not treat these parameters as effective controls for Argon's randomness; the page says Gemini 4 ignores custom values for them.
Keep clear, specific task instructions, constraints, response formats, and necessary few-shot examples.
Use structured delimiters (such as XML-style tags or Markdown headings) to distinguish roles, constraints, context, and tasks. This is a Gemini 3 prompting principle given on the page and must not be rewritten as Argon-specific API behavior.
model: gemini-4-argon
Forbidden custom parameters: temperature, top_p, top_k
The prompt must specify: task, constraints, output formatThe model ID and parameter-removal rule above correspond to the page's explicit coverage of the Gemini 4 restriction. The page does not show a directly copyable Argon API request body, so no SDK or REST schema is added.
Establish an Argon baseline with a fixed prompt and fixed input, recording the request configuration, response, warning headers, and HTTP status.
Send separate requests containing custom temperature, top_p, and top_k values. Record whether the current version ignores them and whether it returns a deprecation-warning header.
Retry the same request after removing the three parameters, and compare the response, status, and warnings. Do not attribute any difference to the three parameters having taken effect.
Prepare a failure case for future compatibility: when the service upgrades the deprecation warning to 400, configuration validation should reject these three fields before sending the request.
Iterate separately on clear instructions, constraints, formats, and few-shot examples in the prompt. Do not rename example code for another Gemini version and present it as Argon code.
The page header says: Gemini 4 Argon is now available. Try it out.
The “Experiment with model parameters” section explicitly says that temperature, top_p, and top_k control how earlier models generate output.
The same note explicitly says: Gemini 4 and Gemini 3.6+ models ignore custom values for temperature, top_p, and top_k, and return a deprecation-warning header; future versions will return a 400 error.
The page's prescribed handling is: Remove temperature, top_p, and top_k from your request configurations.
The page also recommends retaining the default values of these parameters for earlier Gemini 3 models to avoid degraded reasoning performance. That recommendation does not apply to Gemini 4 Argon; rules for earlier versions must not be transferred to Argon.
The visible examples on the page use gemini-2.5-flash, and the Gemini 3 topic examples use Gemini 3. These model names have not been rewritten as Argon.
The original does not show complete gemini-4-argon call code, an SDK version, an authentication method, replacement sampling parameters, pricing, or quality comparisons.
The original states the parameter restriction for the “Gemini 4” family and does not repeat the gemini-4-argon string in that note. This article applies it only to Gemini 4 Argon, which the page explicitly shows as available, and does not extrapolate it to other unlisted models.
The current behavior is to ignore custom values and return a deprecation-warning header; the future behavior is to return 400. Do not describe the future error as an error that already occurs.
This rule does not mean Argon supports an alternative sampling parameter not listed on the page, nor does it mean the page provides a complete API schema.
The page's other advice on clear instructions, few-shot examples, context, structured prompting, and Agentic workflows is general or Gemini 3 content. It can inform prompt design, but must not be presented as an Argon-exclusive capability.
The page does not explain the specific effect of removing these parameters on price, latency, quality, or reasoning tokens. Do not infer those metrics from the parameter restriction.
In the target Gemini API environment, fix model="gemini-4-argon" and prepare a baseline request without sampling parameters; use the current API documentation for the exact request structure.
Copy the same request and add custom temperature, top_p, and top_k values separately, saving the HTTP status, response headers, and response body.
Check whether the current version produces a deprecation-warning header, and confirm that the service does not treat the custom values as effective Argon sampling controls.
Run the request again after deleting the three fields; keep the future-version 400 compatibility check as a pending verification item.
Do not use the page's gemini-2.5-flash or Gemini 3 examples as Argon request code; the page does not publish a complete Argon-specific schema.
Gemini 4 Argon