# Gemini 3.1 Pro Preview Custom Tools

> Gemini 3.1 Pro Preview Custom Tools is a proprietary language model from Google DeepMind, released on 19 Feb 2026. It accepts text, images, video, audio and PDFs and generates text, with a 1M-token context window and up to 66K output tokens per response. As of 4 Oct 2026, the lowest listed API price is $2 per million input tokens and $12 per million output tokens (Gemini API), across 4 providers we track.

Source page: https://www.aimodel.directory/models/gemini-3-1-pro-preview-customtools
Last verified: 4 Oct 2026

## Specifications

- **Developer:** Google DeepMind
- **Release date:** 19 Feb 2026 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Status:** Generally available (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Weights:** Proprietary (API only) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Context window:** 1M (1,048,576 tokens) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Max output:** 66K tokens (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Knowledge cutoff:** Jan 2025 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Input:** Text, images, video, audio and PDFs (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Output:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Reasoning mode:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Tool calling:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)
- **Structured output:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/google/models/gemini-3.1-pro-preview-customtools.toml)

## API pricing (USD per 1M tokens)

| Provider | Input | Output | Cached input | Context |
|---|---|---|---|---|
| Gemini API | $2 | $12 | $0.20 | 1M |
| Google Vertex AI | $2 | $12 | $0.20 | 1M |
| Databricks | $2 | $12 | $0.20 | 1M |
| OpenRouter | $2 | $12 | $0.20 | 1M |

## FAQ

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

Gemini 3.1 Pro Preview Custom Tools has a context window of 1,048,576 tokens (1M) and can generate up to 65,536 tokens in a single response, according to models.dev.

### How much does the Gemini 3.1 Pro Preview Custom Tools API cost?

Through Gemini API, Gemini 3.1 Pro Preview Custom Tools costs $2 per million input tokens and $12 per million output tokens. Prices last verified 4 Oct 2026.

### Is Gemini 3.1 Pro Preview Custom Tools open source?

No. Gemini 3.1 Pro Preview Custom Tools is a proprietary model; Google DeepMind has not released its weights. It is available through APIs including Gemini API, Google Vertex AI, Databricks, OpenRouter.

### When was Gemini 3.1 Pro Preview Custom Tools released?

Google DeepMind released Gemini 3.1 Pro Preview Custom Tools on 19 Feb 2026, according to models.dev.

### Which providers offer Gemini 3.1 Pro Preview Custom Tools?

We track Gemini 3.1 Pro Preview Custom Tools on 4 providers: Gemini API, Google Vertex AI, Databricks, OpenRouter.

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Data licensed CC BY 4.0. Cite as: AI Model Directory, "Gemini 3.1 Pro Preview Custom Tools", https://www.aimodel.directory/models/gemini-3-1-pro-preview-customtools