Gemini 3.1 Pro Preview Custom Tools

Name: Google Gemini 3.1 Pro Preview Custom Tools
Price: 1.7 USD
Availability: InStock
Author: Google

15% OFFgoogle/gemini-3.1-pro-preview-customtools

Gemini 3.1 Pro Preview Custom Tools is a separate endpoint of Google's Gemini 3.1 Pro Preview, the Pro-tier reasoning model of the Gemini 3 series, tuned for agentic workflows that mix bash with custom tools. Google says it is better at prioritizing user-defined functions, such as file viewing or code search tools, over a general bash tool. Pick it for coding agents built on custom tools; Google notes quality may fluctuate in use cases that do not benefit from such tools, where the standard 3.1 Pro Preview fits better.

Use in agent Get API key

Input price: $1.70~~$2.00~~USD / 1M tokens
Output price: $10.20~~$12.00~~USD / 1M tokens
Context window: 1M
Max output: 65.5K

Production route

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Prompt

Image URL or upload

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1M context65.5K max outputVision

Input~~$2.00/M~~$1.70/MOutput~~$12.00/M~~$10.20/MCache read~~$0.20/M~~$0.17/M

15% OFF

OutputReady

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Choose an example or write a prompt, then click Run.

Model card

Specifications

Pricing

Input: $1.70 / 1M tokens
Output: $10.20 / 1M tokens
Cache read: $0.17 / 1M tokens

Context & modalities

Context window: 1,048,576 tokens
Max output: 65,536 tokens
Input: Text, image
Output: Text

Capabilities

Chat: Supported
Vision: Supported
Reasoning: Supported
Structured output: Supported
Function calling: Supported
Audio input: Supported

Access

Provider: Google
Model ID: google/gemini-3.1-pro-preview-customtools
Execution: sync
Base URL: https://api.sandbase.ai
API: Chat Completions API
Endpoint: /v1/chat/completions

Start building

Send your first request

OpenAI-compatible endpoint with unified authentication and usage tracking.

Production API

Chat Completions API endpoint

https://api.sandbase.ai/v1/chat/completions

Model ID

google/gemini-3.1-pro-preview-customtools

# The quoted heredoc keeps Unicode and shell metacharacters unchanged.
result=$(curl --fail-with-body --silent \
  -X POST "https://api.sandbase.ai/v1/chat/completions" \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'SANDBASE_JSON'
{
  "model": "google/gemini-3.1-pro-preview-customtools",
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ],
  "max_tokens": 2048
}
SANDBASE_JSON
)
printf '%s\n' "$result"

Choose your model

Compare models

All language models

Model	Context	Input / 1M	Output / 1M	Released
Gemini 3.1 Pro Preview Custom ToolsThis model `Google`	1M	$1.70	$10.20	Feb 25, 2026
Gemini 4 Argon `Google`	1M	$4.00	$20.00	Oct 13, 2026
Nano Banana 2.1 (Gemini Nano Banana 2.1) `Google`	64K	$1.50	$7.50	Oct 8, 2026
Gemini 3.8 Flash `Google`	1M	$1.50	$7.50	Sep 2, 2026
Gemini 3.7 Flash `Google`	1M	$1.50	$7.50	Aug 13, 2026
Gemini 3.5 Flash Lite `Google`	1M	$0.30	$2.50	Jul 21, 2026

Questions

FAQ

How do I call Google Gemini 3.1 Pro Preview Custom Tools through SandBase?

Create a SandBase API key, then send requests with the model ID "google/gemini-3.1-pro-preview-customtools" to Chat Completions API (/v1/chat/completions) at https://api.sandbase.ai. The request examples on this page show the exact payload.

How much does Google Gemini 3.1 Pro Preview Custom Tools cost?

$1.70 per 1M input tokens and $10.20 per 1M output tokens with the current 15% discount (list price $2 / $12), billed per request from your SandBase balance.

What is the context window of Google Gemini 3.1 Pro Preview Custom Tools?

1M tokens of context, with up to 65.5K output tokens per response.

Which features does Google Gemini 3.1 Pro Preview Custom Tools support?

Google Gemini 3.1 Pro Preview Custom Tools supports vision (image input), reasoning, function calling, structured output. See Specifications above for the full list.

Do I need a separate Google account?

No. One SandBase API key and balance gives you access to Google Gemini 3.1 Pro Preview Custom Tools and the other models in the catalog; you do not need to sign up with Google separately.