Vertex Gemini 2.5 Pro API parameters
These are the API parameters modelparams.dev tracks for Vertex Gemini 2.5 Pro — the settings you send in a request. Each row gives the type, default, valid range or values, and the conditions that gate it. It's the same data the JSON API serves.
This model is deprecated. Shutdown date: 2026-10-20. Suggested replacement: vertex/gemini-3.5-flash.
After the parameter count instead — how many weights Gemini 2.5 Pro has? That's a different number, and we don't track it. Here's the difference.
Length
3 params
| Parameter | Type | Default | Description | Condition |
|---|---|---|---|---|
|
Max output tokens
generationConfig.maxOutputTokens
|
integer (1…65536) | — | Maximum number of tokens to include in a response candidate. | — |
|
Candidate count
generationConfig.candidateCount
|
integer (1…8) | — | How many independent completions to generate for one request. | — |
|
Stop sequences
generationConfig.stopSequences
|
string | — | A list of strings where the model stops generating further tokens. | — |
Sampling
6 params
| Parameter | Type | Default | Description | Condition |
|---|---|---|---|---|
|
Temperature
generationConfig.temperature
|
number (0…2 step 0.1) | 1 | Controls randomness. Lower values make outputs more focused; higher values make them more varied. | — |
|
Top P
generationConfig.topP
|
number (0…1 step 0.01) | 0.95 | Controls nucleus sampling by limiting generation to tokens within the selected cumulative probability. | — |
|
Top K
generationConfig.topK
|
integer (1…+∞) | 64 | Limits token sampling to the top K most likely next tokens. | — |
|
Seed
generationConfig.seed
|
integer | — | Optional seed used for decoding when reproducible sampling is desired. | — |
|
Presence penalty
generationConfig.presencePenalty
|
number (-2…1) | — | Penalises tokens that already appeared, pushing the model toward new topics. | — |
|
Frequency penalty
generationConfig.frequencyPenalty
|
number (-2…1) | — | Penalises tokens in proportion to how often they have already appeared. | — |
Reasoning
2 params
| Parameter | Type | Default | Description | Condition |
|---|---|---|---|---|
|
Thinking budget
generationConfig.thinkingConfig.thinkingBudget
|
integer (0…+∞) | — | Token budget the model may spend on internal reasoning before answering. 0 disables thinking. Cannot be combined with thinkingLevel. | — |
|
Include thoughts
generationConfig.thinkingConfig.includeThoughts
|
boolean | false | Controls whether Gemini returns available thought summaries in the response parts. | — |
Output
1 param
| Parameter | Type | Default | Description | Condition |
|---|---|---|---|---|
|
Response MIME type
generationConfig.responseMimeType
|
enum (text/plain | application/json) | "text/plain" | MIME type for generated text candidates. | — |
Vertex Gemini 2.5 Pro API parameters in brief
Vertex Gemini 2.5 Pro documents 12 API parameters, grouped by what they control:
-
Length:
generationConfig.maxOutputTokensrange 1–65536;generationConfig.candidateCountrange 1–8;generationConfig.stopSequences. -
Sampling:
generationConfig.temperaturedefaults to 1, range 0–2;generationConfig.topPdefaults to 0.95, range 0–1;generationConfig.topKdefaults to 64, minimum 1;generationConfig.seed;generationConfig.presencePenaltyrange -2–1;generationConfig.frequencyPenaltyrange -2–1. -
Reasoning:
generationConfig.thinkingConfig.thinkingBudgetminimum 0;generationConfig.thinkingConfig.includeThoughtsdefaults to false. -
Output:
generationConfig.responseMimeTypedefaults to "text/plain", accepts "text/plain", "application/json".
Frequently asked questions
- Which API parameters does Vertex Gemini 2.5 Pro support?
- Vertex Gemini 2.5 Pro accepts 12 API parameters in the request body: generationConfig.maxOutputTokens, generationConfig.temperature, generationConfig.topP, generationConfig.topK, generationConfig.seed, generationConfig.candidateCount, and more.
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