Gemini 3.1 Pro Preview Custom Tools
About this model
Gemini 3.1 Pro Preview Custom Tools is an AI model from Google DeepMind, made available through the API on February 25, 2026. It can read up to 1,048,576 tokens in one request, roughly 1,966 pages of text, and write up to 65,536 tokens in a single answer. Besides text, it accepts audio, images, video and files such as PDFs as input.
Through the API it costs $2 per million input tokens and $12 per million output tokens. It is among the more expensive models we track, a price usually reserved for the most capable, flagship-class models.
It supports extended reasoning: it can "think" step by step before answering, which helps on maths, code and complex questions. It can call tools and functions, so developers can connect it to search, databases or other software.
Quality scores
Rankings →- SWE-bench VerifiedCan the model fix real bugs in real open-source software projects? Share of tasks solved.75.6%#11 of 28
Where to use it
Companies that serve this model through an API: 1. Prices per million tokens, cheapest first.
Availability and prices come from OpenRouter’s public API and are refreshed daily. Uptime is the share of successful requests over the last 24 hours. Some providers run a compressed version of open models (fp8, int4), which is cheaper but can be slightly less accurate.
Use it in your code
Call Gemini 3.1 Pro Preview Custom Tools through OpenRouter’s OpenAI-compatible API: create a key on openrouter.ai, then run one of these examples.
curl https://openrouter.ai/api/v1/chat/completions \
-H "Authorization: Bearer $OPENROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model": "google/gemini-3.1-pro-preview-customtools", "messages": [{"role": "user", "content": "Hello! What can you do?"}]}'import os
from openai import OpenAI
client = OpenAI(base_url="https://openrouter.ai/api/v1", api_key=os.environ["OPENROUTER_API_KEY"])
reply = client.chat.completions.create(
model="google/gemini-3.1-pro-preview-customtools",
messages=[{"role": "user", "content": "Hello! What can you do?"}],
)
print(reply.choices[0].message.content)import OpenAI from "openai";
const client = new OpenAI({ baseURL: "https://openrouter.ai/api/v1", apiKey: process.env.OPENROUTER_API_KEY });
const reply = await client.chat.completions.create({
model: "google/gemini-3.1-pro-preview-customtools",
messages: [{ role: "user", content: "Hello! What can you do?" }],
});
console.log(reply.choices[0].message.content);The same code works with every model on this site: only the model ID changes. Many labs also offer their own API and SDK.
What it costs in practice
- 1,000 chat replies$4.60
- Summarise a 100-page document$0.112
- An app with 10,000 requests a day for a month$2,040
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News about Google DeepMind
See all →Frequently asked questions
- How much does Gemini 3.1 Pro Preview Custom Tools cost?
- Gemini 3.1 Pro Preview Custom Tools costs $2 per million input tokens and $12 per million output tokens through the API. For example, 1,000 chat replies of about 500 tokens in and 300 out cost around $4.60.
- What is the context window of Gemini 3.1 Pro Preview Custom Tools?
- Gemini 3.1 Pro Preview Custom Tools can read up to 1,048,576 tokens in one request, about 1,966 pages of text. It can write up to 65,536 tokens in a single answer.
- Is Gemini 3.1 Pro Preview Custom Tools open source?
- No. Gemini 3.1 Pro Preview Custom Tools is a closed model: its weights are not published, so you use it through Google DeepMind’s own apps and API, or through cloud providers.
- Who makes Gemini 3.1 Pro Preview Custom Tools?
- Gemini 3.1 Pro Preview Custom Tools is made by Google DeepMind. It became available through the API on February 25, 2026.
- Can Gemini 3.1 Pro Preview Custom Tools read images?
- Yes. Besides text, it accepts audio, images, video and files such as PDFs as input.
- What are the alternatives to Gemini 3.1 Pro Preview Custom Tools?
- Models with a similar price from other companies include GPT-6.1 Sol Pro, Claude Sonnet 5.5 and Grok 4.7. You can compare them side by side on this page.