---
title: Gemini 3.1 Pro Custom Tools — Agentic LLM | ModelsLab
description: Access Google Gemini 3.1 Pro Preview Custom Tools API for optimized tool calling and multimodal reasoning. Try agentic workflows now.
url: https://modelslab.com/google-gemini-31-pro-preview-custom-tools
canonical: https://modelslab.com/google-gemini-31-pro-preview-custom-tools
type: website
component: Seo/ModelPage
generated_at: 2026-04-23T03:03:04.228092Z
---

Available now on ModelsLab · Language Model

Google: Gemini 3.1 Pro Preview Custom Tools
Tools First Reasoning
---

[Try Google: Gemini 3.1 Pro Preview Custom Tools](/models/open_router/google-gemini-3.1-pro-preview-customtools) [API Documentation](https://docs.modelslab.com)

Build Agentic Workflows
---

Tool Priority

### Custom Tools Optimized

Prioritizes registered custom tools over bash in agentic flows.

Multimodal Input

### 1M Token Context

Handles text, images, video, audio with 1,048,576 token window.

Reasoning Enabled

### Step-by-Step Thinking

Supports code execution, function calling, structured outputs.

Examples

See what Google: Gemini 3.1 Pro Preview Custom Tools can create
---

Copy any prompt below and try it yourself in the [playground](/models/open_router/google-gemini-3.1-pro-preview-customtools).

Code Search

“Find all Python files containing 'TODO' in the project directory. List file paths and line numbers with context.”

File Analysis

“Analyze this uploaded PDF schematic. Identify components, map connections, flag missing dependencies.”

Data Query

“Search codebase for functions using 'search\_code' tool. Summarize usage patterns and suggest optimizations.”

Multimodal Task

“View this image of a circuit board. Extract handwritten notes, simulate 3D model, generate interactive code preview.”

For Developers

A few lines of code.
Tools. One call.
---

ModelsLab handles the infrastructure: fast inference, auto-scaling, and a developer-friendly API. No GPU management needed.

- **Serverless:** scales to zero, scales to millions
- **Pay per token,** no minimums
- **Python and JavaScript SDKs,** plus REST API

[API Documentation ](https://docs.modelslab.com)

PythonJavaScriptcURL

Copy

```
<code>import requests

response = requests.post(
    "https://modelslab.com/api/v7/llm/chat/completions",
    json={
  "key": "YOUR_API_KEY",
  "prompt": "",
  "model_id": ""
}
)
print(response.json())</code>
```

FAQ

Common questions about Google: Gemini 3.1 Pro Preview Custom Tools
---

[Read the docs ](https://docs.modelslab.com)

### What is Google: Gemini 3.1 Pro Preview Custom Tools?

Specialized variant of Gemini 3.1 Pro released February 19, 2026. Optimizes for agentic workflows by prioritizing custom tools over bash commands. Model ID: gemini-3.1-pro-preview-customtools.

### How does google gemini 3.1 pro preview custom tools differ from standard?

Prioritizes user-defined tools like view_file or search_code. Quality may fluctuate without tools. Same pricing as Gemini 3.1 Pro.

### What is Google: Gemini 3.1 Pro Preview Custom Tools API context window?

Supports 1,048,576 tokens input, 65,536 tokens output. Multimodal: text, image, video, audio, PDF.

### Is Google: Gemini 3.1 Pro Preview Custom Tools model good for agents?

Yes, excels in tool calling, reasoning, code execution. Use for multi-step tasks and custom integrations.

### Where to find Google: Gemini 3.1 Pro Preview Custom Tools alternative?

Available via Gemini API endpoint generativelanguage.googleapis.com. Integrates with OpenAI-compatible clients on platforms like OpenRouter.

### Does google gemini 3.1 pro preview custom tools api support caching?

Yes, caching supported at $0.2 per 1M tokens read. Pricing: $2 input, $12 output per 1M tokens.

Ready to create?
---

Start generating with Google: Gemini 3.1 Pro Preview Custom Tools on ModelsLab.

[Try Google: Gemini 3.1 Pro Preview Custom Tools](/models/open_router/google-gemini-3.1-pro-preview-customtools) [API Documentation](https://docs.modelslab.com)

---

*This markdown version is optimized for AI agents and LLMs.*

**Links:**
- [Website](https://modelslab.com)
- [API Documentation](https://docs.modelslab.com)
- [Blog](https://modelslab.com/blog)

---
*Generated by ModelsLab - 2026-04-23*