GoogleFastReleased 25 February 2026
Gemini 3.1 Pro Preview Custom Tools pricing, context and benchmark
Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party...
1.05M
Input context
66K
Output context
$2
Official input
$12
Official output
n/a
AA index
01 · Model Overview
Everything that matters, in one table
Context, pricing, cache, modalities and tooling, from the model registry and Artificial Analysis.
| Model | Gemini 3.1 Pro Preview Custom Tools |
| Model ID | google/gemini-3.1-pro-preview-customtools |
| Provider | |
| Release date | 25 February 2026 |
| Status | Generally available |
| Input context | 1,048,576 tokens |
| Output context | 65,536 tokens |
| Official input pricing | $2 per 1M tokens |
| Official output pricing | $12 per 1M tokens |
| Cache read pricing | $0.2 per 1M tokens |
| Market input pricing | $2 per 1M (cheapest route) |
| Market output pricing | $12 per 1M (cheapest route) |
| Reasoning tokens | Billed as output at $12 per 1M |
| Input modalities | text · audio · image · video · file |
| Output modalities | text |
| Reasoning control | Yes, effort levels exposed |
| Tool support | Functions, tool choice, structured outputs |
| Tokenizer | Gemini |
| Provider routes | 1 endpoint |
| Artificial Analysis index | Not published |
| Speed | Not published |
| Knowledge cutoff | Not publicly stated |
Input and output support
| Modality | Input | Output | Billed at |
|---|---|---|---|
| Text | ✓ yes | ✓ yes | $2 in |
| Image | ✓ yes | no | $2 in |
| Audio | ✓ yes | no | $2 in |
| Video | ✓ yes | no | $2 in |
| File (PDF) | ✓ yes | no | $2 in |
02 · Overview
What is Gemini 3.1 Pro Preview Custom Tools?
Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party...
Gemini 3.1 Pro Preview Custom Tools carries a 1.05M token window, uses the Gemini tokenizer and is served by Google. On Hoodgen it sits in the Fast tier of the model menu next to its siblings, so you can switch mid conversation without losing the thread.
03 · Release
Release and what changed from the previous version
Released25 February 2026
| Property | Gemini 3.1 Pro Preview | Gemini 3.1 Pro Preview Custom Tools | Change |
|---|---|---|---|
| Released | 2026 | 2026 | Same release window |
| Context | 1.05M | 1.05M | Unchanged |
| Max output | 66K | 66K | Unchanged |
| Input price | $2 | $2 | Unchanged |
| Output price | $12 | $12 | Unchanged |
| Input modalities | audio, file, image, text, video | text, audio, image, video, file | Unchanged |
| AA index | n/a | n/a | Newer benchmark run |
04 · Capabilities
Features and capabilities
◈
Thinking control
Reasoning effort can be dialled per request, so one model covers deep analysis and fast chat.
⚙
Function calling
Tools, tool choice and parallel calls, which is what agent loops need to act on results.
{ }
Structured outputs
Schema constrained JSON with response_format, so no parse and retry loop in your code.
◉
Vision
Screenshots, charts and photographed documents are read at the text token rate.
▤
Files and PDFs
Documents go in as files rather than pasted text, keeping layout and tables intact.
♪
Audio and video
Calls, meetings and screen recordings can be summarised in one pass.
⚡
Prompt caching
Cached input costs $0.2 per million instead of $2, so stable prefixes get cheaper.
⌁
Seeds
A seed can be pinned so the same prompt is reproducible across test runs.
05 · Reasoning
Thinking and reasoning capabilities
Gemini 3.1 Pro Preview Custom Tools can think before answering and exposes the effort level per request. Reasoning tokens bill as output at $12 per million, and the trace can be returned with include_reasoning.
| Level | First token | Cost per task | Best for |
|---|---|---|---|
| Measured | n/a | n/a | Artificial Analysis measures the default reasoning configuration |
| Low effort | Faster | Lower | Chat, autocomplete, classification |
| High effort | Slower | Higher | Debugging, planning, multi step agents |
07 · Use cases
What can you do with Gemini 3.1 Pro Preview Custom Tools?
High volume drafts
Captions, titles, product blurbs and rewrite passes where cost per call dominates.
Inline assistants
Autocomplete, quick replies and menu helpers that must answer inside a second.
Batch classification
Tagging, routing and extraction across thousands of short inputs.
Cheap agent loops
Tool calling loops that do not need frontier grade reasoning.
08 · Cost levers
Prompt caching and how to cut the bill
Cached input bills at $0.2 per million instead of $2. Keep the system prompt and documents first and the changing question last, so every call hits the cache.
09 · Pricing
Gemini 3.1 Pro Preview Custom Tools pricing
Official pricing
List price
$2 / 1M in
$12 / 1M out
- $0.2 cached input
- 1.05M context
- text, audio, image, video, file input
Cheapest route
$2 / 1M in
$12 / 1M out
- 1 route on OpenRouter
- What Hoodgen routes to first
- Same model, lower bill
Market pricing, every route
| Provider | Tier | Input | Output | Cache read | Uptime 24h |
|---|---|---|---|---|---|
| Google AI Studio | standard | $2 | $12 | $0.2 | 100.0% |
API pricing and cost calculator
| Rate | Per call | Total | Credits |
|---|---|---|---|
| Cheapest route | $0.0364 | $18.20 | 17290 |
| List price | $0.0364 | $18.20 | 17290 |
10 · Developers
API and developer information
| Model ID | google/gemini-3.1-pro-preview-customtools |
| Endpoint | https://openrouter.ai/api/v1/chat/completions |
| Parameters | include_reasoning · max_tokens · reasoning · reasoning_effort · response_format · seed · structured_outputs · temperature · tool_choice · tools · top_p |
| Streaming | Yes, server sent events |
| Modality string | text+image+file+audio+video->text |
| Max prompt tokens | 1,048,576 |
| Max completion tokens | 65,536 |
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": "Summarise this document." }],
"max_tokens": 1024
}'11 · Limitations
Model limitations
| Text only output | It cannot generate images, audio or video. Pair it with an image model on Hoodgen when you need visuals. |
| Output cap | 65,536 tokens per request. Long deliverables have to be chunked. |
| Benchmarks not published | Artificial Analysis does not publish an Intelligence Index for this release, so no benchmark score is claimed here. |
| Knowledge cutoff | The provider does not state a fixed cutoff for every release. Verify very recent events against search. |
| Depth ceiling | Fast tier: strong on throughput, weaker than flagship tiers on long multi step reasoning. |
12 · Comparison
Gemini 3.1 Pro Preview Custom Tools vs other Google models
| Model | Context | Input /1M | Output /1M | AA index | Released |
|---|---|---|---|---|---|
| Gemini 3.1 Pro Preview Custom Tools | 1.05M | $2 | $12 | n/a | 2026 |
| Gemini 3.1 Pro Preview | 1.05M | $2 | $12 | n/a | 2026 |
| Gemini 4 Argon | 1.05M | $2 | $10 | 50 | Oct 2026 |
| Gemini 4 Carbon | 1.05M | $2 | $10 | n/a | 2026 |
| Nano Banana Pro (Gemini 3 Pro Image) | 131K | $2 | $12 | n/a | 2026 |
| Nano Banana Pro (Gemini 3 Pro Image Preview) | 66K | $2 | $12 | n/a | 2025 |
13 · Privacy
Privacy and data policy
- On Hoodgen, prompts and attachments answer that request and stay in your conversation history so you can reopen it. They are not used to train models.
- Requests route through OpenRouter to Google and are covered by that provider's API terms.
- Do not paste secrets or personal data you would not send to any hosted model.
14 · FAQ
Gemini 3.1 Pro Preview Custom Tools questions, answered
Gemini 3.1 Pro Preview Custom Tools is a fast model from Google, released 25 February 2026. Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party...
✦
Start chatting with Gemini 3.1 Pro Preview Custom Tools
Free to try on Hoodgen AI, with a live credit estimate before every send. No API key, no setup.