Google: Gemini 3.1 Pro Preview Custom Tools
Gemini 3.1 Pro Preview Custom Tools is a reasoning model from Google released on Feb 19, 2026. It reads text, images, files, audio and video and writes text, with a 1.05M token context window and up to 66K tokens per reply.
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It costs $2 per million input tokens and $12 per million output tokens. Cached input bills at $0.20, 90% less than fresh input.
It supports tool calling, structured JSON output and prompt caching.
12 providers serve it, including Databricks, Vertex and AIHubMix.
- Modalities
- In / out price
- $2 / $12 per 1M
- Context
- 1.05M
- Max output
- 66K
- Released
- Feb 19, 2026
- Knowledge cutoff
- Jan 2025
- Tool calling
- Structured output
- Reasoning
- Prompt caching
- Open weights
- Free to use
Gemini 3.1 Pro Preview Custom Tools pricing
USD, as listed on Oct 15, 2026. Most bills are input heavy, so the cached input rate matters as much as the headline price.
| Input | $2 / 1M tokens | |
|---|---|---|
| Output | $12 / 1M tokens | |
| Cached input (read) | $0.20 / 1M tokens | 90% off input |
| Prompts over 200K | $4 in, $18 out | long context rate |
| Prompts over 200K | $4 in, $18 out | long context rate |
Gemini 3.1 Pro Preview Custom Tools providers
12 providers serve it, including Databricks, Vertex and AIHubMix. Each host sets its own price and limits, so the cheapest one is not always the one with the longest context.
| Provider | Input /M | Output /M | Cache read /M | Context | Max output |
|---|---|---|---|---|---|
| Google First party | $2 | $12 | $0.20 | 1.05M | 66K |
| Databricks | $2 | $12 | $0.20 | 1.05M | 66K |
| Vertex | $2 | $12 | $0.20 | 1.05M | 66K |
| AIHubMix | $2 | $12 | $0.20 | 1.05M | 66K |
| Eden AI | $2 | $12 | $0.20 | 1.05M | 66K |
| Kilo Gateway | $2 | $12 | $0.20 | 1.05M | 66K |
| Merge Gateway | $2 | $12 | $0.20 | 1.05M | 66K |
| NanoGPT | $2 | $12 | $0.20 | 1.05M | 66K |
| Neon | $2 | $12 | $0.20 | 1.05M | 66K |
| OrcaRouter | $2 | $12 | $0.20 | 1.05M | 66K |
| Tempr Gateway | $2 | $12 | $0.20 | 1.05M | 66K |
| AI/ML API | $2.75 | $16.50 | $0.2751 | 1.05M | 66K |
What Gemini 3.1 Pro Preview Custom Tools costs per month
Pick a workload close to yours or type your own volumes.
Supported request parameters
What you can set when you call Gemini 3.1 Pro Preview Custom Tools through an OpenAI compatible API.
- Tools
tools - Structured outputs
structured_outputs - Reasoning
reasoning - Temperature
temperature
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Gemini 3.1 Pro Preview Custom Tools questions
How much does the Gemini 3.1 Pro Preview Custom Tools API cost?
$2 per million input tokens and $12 per million output tokens, with cached input at $0.20. Prompts over 200K tokens bill at $4 input and $18 output. The estimator on this page turns that into a monthly bill for your own workload.
What is the context window of Gemini 3.1 Pro Preview Custom Tools?
1,048,576 tokens of input, and it can write up to 65,536 tokens in one reply. As a rough guide, a million tokens is around 750,000 English words.
Which providers serve Gemini 3.1 Pro Preview Custom Tools?
12 providers serve it, including Databricks, Vertex and AIHubMix. Prices differ by host, so the Providers table on this page lists each one with its input and output price.
Does Gemini 3.1 Pro Preview Custom Tools support tool calling?
Yes. It accepts tool definitions and can return JSON that matches a schema, which is what an agent needs to call your APIs.
Is Gemini 3.1 Pro Preview Custom Tools open source?
No. Google serves it through an API only, so you cannot download the weights or host it yourself.
When was Gemini 3.1 Pro Preview Custom Tools released?
Feb 19, 2026, with training data up to Jan 2025.
Catalog data from models.dev (MIT licensed), refreshed daily, last on Oct 15, 2026. The summary is written from these facts.
Building on Gemini 3.1 Pro Preview Custom Tools?
I test your real tasks on it and the two closest alternatives, then ship the agent on whichever wins on cost and accuracy.
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