Gemini 3.1 Pro Preview Custom Tools API

google/gemini-3.1-pro-preview-customtools
Gemini 3.1 Pro Preview Custom Tools on AIMLAPI.
Context
1.05M tokens
Input
$2.7508 / 1M tokens
Output
$16.5048 / 1M tokens

How to use Gemini 3.1 Pro Preview Custom Tools API

Install any OpenAI-compatible SDK, point it at api.aimlapi.com/v1, and set the model to google/gemini-3.1-pro-preview-customtools.
import requests

r = requests.post(
    "https://api.aimlapi.com/v1/chat/completions",
    headers={"Authorization": "Bearer " + AIMLAPI_KEY},
    json={
      "model": "google/gemini-3.1-pro-preview-customtools",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ]
    },
)
print(r.json())
const r = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "google/gemini-3.1-pro-preview-customtools",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ]
  }),
});
console.log(await r.json());
curl -X POST https://api.aimlapi.com/v1/chat/completions \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"google/gemini-3.1-pro-preview-customtools","messages":[{"role":"user","content":"Hello!"}]}'

OpenAI-compatible — swap the base URL and it works with your existing SDK.

Gemini 3.1 Pro Preview Custom Tools API Pricing

TypePrice
Input
$2.7508 / 1M tokens
Output
$16.5048 / 1M tokens
Cached input
$0.27508 / 1M tokens

Gemini 3.1 Pro Preview Custom Tools vs other models

ModelInputOutputContextBest for
$2.7508 / 1M tokens
$16.5048 / 1M tokens
1.05M tokens
Reasoning + agents
$6.5 / 1M tokens
$39 / 1M tokens
1.05M tokens
Reasoning + agents
$2.6 / 1M tokens
$13 / 1M tokens
1M tokens
Balanced coding + agents
$3.9 / 1M tokens
$19.5 / 1M tokens
1M tokens
Long-context, multimodal & agentic workflows
$0.65 / 1M tokens
$3.9 / 1M tokens
1.05M tokens
Reasoning + agents

Frequently asked questions

Gemini 3.1 Pro Preview Custom Tools has a 1,048,756 tokens context window and can return up to 65,536 tokens.

Gemini 3.1 Pro Preview Custom Tools takes image, text as input and returns text.

Use google/gemini-3.1-pro-preview-customtools as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

Gemini 3.1 Pro Preview Custom Tools is priced at input $2.7508 / 1M tokens, output $16.5048 / 1M tokens, cached input $0.27508 / 1M tokens.

Yes, Gemini 3.1 Pro Preview Custom Tools can stream responses as they are generated.

Yes, Gemini 3.1 Pro Preview Custom Tools accepts image input alongside text.

Gemini 3.1 Pro Preview Custom Tools was built by Google.

It supports function calling, reasoning, structured outputs, web search, and parallel tool calls, making it suited for tasks that combine multi-step reasoning with tool use.

Start building with Gemini 3.1 Pro Preview Custom Tools

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