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Gemini 3.1 Pro (Preview Custom Tools)

Added Feb 27, 2026

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Use in the app

Gemini 3.1 Pro preview variant tuned for better tool selection behavior in coding agents and multi-tool workflows. It reduces overuse of generic bash tools and improves function-calling reliability while retaining Gemini 3.1 Pro's multimodal reasoning and 1M-token context. NOTE: Inputs > 200k tokens are charged at 2x input and 1.5x output rates.

  • Reasoning
  • Tools
  • Vision
  • Structured output
  • Audio input
  • Video input
Input
Text, Images, Video, Audio
Output
Text
Reasoning effort
low · medium · high
Discovery tier
Frontier

Pricing

USD per 1M tokens
Input
$2.00
Output
$12.00
Cache read
$0.20
Cache write
$0.38

Reference prices as published by the model provider. API example

Specifications

Context window
1M
Max output
65.5K
Average output (7 days)
903 tokens
Longer than 68% of 465 models

Side by side

Gemini 3.1 Pro (Preview Custom Tools) compared

Specifications, prices, speed and benchmark scores next to each other. Benchmarks below show every compared model too.

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Gemini 3.1 Pro (Preview Custom Tools)GoogleThis modelDiffusionGemmaGoogleRemove
ProviderGoogleGoogle
Discovery tierFrontierOpen weights
AddedFeb 27, 2026Sep 19, 2026
Limits
Context window1.05MBest262.14K
Max output65.54KBest32.77K
Average output903 tokens266 tokens
Pricing, USD per 1M tokens
Input$2.00$0.05Best
Output$12.00$0.15Best
Cache read$0.20$0.025Best
Cache write$0.38—
Benchmark indexes
Intelligence Index29.7Best9.5
Coding Index68.8Best19.7
Capabilities
ReasoningYesYes
ToolsYesNo
VisionYesNo
Structured outputYesNo
Audio inputYesNo
Video inputYesNo
Reasoning effortlow, medium, highnone, xhigh

Public evaluations

Benchmarks

Independent evaluation results, with how each score ranks among the models in the Noumen catalog.

  • Gemini 3.1 Pro (Preview Custom Tools)
  • DiffusionGemma

Intelligence Index

  • Gemini 3.1 Pro (Preview Custom Tools)29.7
  • DiffusionGemma9.5

Gemini 3.1 Pro (Preview Custom Tools): Better than 71% of 326 scored models

3.8Catalog models by score55.1

Indexes

  • Coding Index

    Composite of the coding evaluations

    • Gemini 3.1 Pro (Preview Custom Tools): 68.8Top
    • DiffusionGemma: 19.7

Agentic work

  • AutomationBench-AA

    Workflow automation, penalized for guardrail violations

    • Gemini 3.1 Pro (Preview Custom Tools): 35.4%
    • DiffusionGemma: —

  • AutomationBench-AA tasks completed

    Workflows finished end to end without a guardrail violation

    • Gemini 3.1 Pro (Preview Custom Tools): 9.4%
    • DiffusionGemma: —

  • Harvey LAB-AAv1.1

    Legal tasks passed in full, with no material hallucination

    • Gemini 3.1 Pro (Preview Custom Tools): 0.0%
    • DiffusionGemma: —

  • AA-Briefcasev1.1

    Agentic knowledge work, rated head to head

    • Gemini 3.1 Pro (Preview Custom Tools): 456 Elo
    • DiffusionGemma: —

  • GDPval-AAv2.1

    Economically valuable occupational tasks, rated head to head

    • Gemini 3.1 Pro (Preview Custom Tools): 791 EloTop
    • DiffusionGemma: 321 Elo

Document reasoning

  • GDP.pdf

    Professional reasoning over PDF documents, all-pass rate

    • Gemini 3.1 Pro (Preview Custom Tools): 17.8%
    • DiffusionGemma: —

  • AA-LCRv1.1

    Reasoning across long documents

    • Gemini 3.1 Pro (Preview Custom Tools): 82.0%Top
    • DiffusionGemma: 19.7%

  • MLCR-AA

    Long-context reasoning over medical records

    • Gemini 3.1 Pro (Preview Custom Tools): 11.1%
    • DiffusionGemma: —

Reasoning and knowledge

  • Humanity’s Last Exam

    Expert-level questions across academic fields

    • Gemini 3.1 Pro (Preview Custom Tools): 47.0%Top
    • DiffusionGemma: 10.8%

  • GPQA Diamond

    Graduate-level science questions

    • Gemini 3.1 Pro (Preview Custom Tools): 94.1%Top
    • DiffusionGemma: 66.9%

  • IFBench

    Following precise output instructions

    • Gemini 3.1 Pro (Preview Custom Tools): 77.1%Top
    • DiffusionGemma: 59.5%

Coding

  • Terminal-Benchv4.0

    Practical software engineering in a terminal

    • Gemini 3.1 Pro (Preview Custom Tools): 4.0%
    • DiffusionGemma: —

  • SciCode

    Scientific computing in Python

    • Gemini 3.1 Pro (Preview Custom Tools): 58.7%
    • DiffusionGemma: —

Legacy evaluations

  • Terminal-Bench Hard

    Earlier terminal task suite

    • Gemini 3.1 Pro (Preview Custom Tools): 53.8%
    • DiffusionGemma: —

  • τ²-Bench Telecom

    Tool use in a customer-support simulation

    • Gemini 3.1 Pro (Preview Custom Tools): 95.6%
    • DiffusionGemma: —

  • AA-LCR (unversioned)

    Long-context reasoning, earlier grading

    • Gemini 3.1 Pro (Preview Custom Tools): 82.0%Top
    • DiffusionGemma: 19.7%

Scores from Artificial Analysis, updated Oct 26, 2026. Artificial Analysis

Developers

Use it through the API

Noumen’s API is OpenAI-compatible: any Chat Completions client works with a base URL and a key.

Read the quickstart
curl https://www.noumen.xyz/api/v1/chat/completions \
  -H "Authorization: Bearer $NOUMEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "google/gemini-3.1-pro-preview-customtools",
    "reasoning_effort": "medium",
    "messages": [{ "role": "user", "content": "Explain this stack trace." }]
  }'
import os
from openai import OpenAI

client = OpenAI(base_url="https://www.noumen.xyz/api/v1", api_key=os.environ["NOUMEN_API_KEY"])
reply = client.chat.completions.create(
    model="google/gemini-3.1-pro-preview-customtools",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

Google

Other Google models, starting with the same family.