Gemini 3.1 Pro Preview Custom Tools vs o3 Deep Research
Gemini 3.1 Pro Preview Custom Tools (2026) and o3 Deep Research (2025) are frontier reasoning models from Google DeepMind and OpenAI. Gemini 3.1 Pro Preview Custom Tools ships a 1m-token context window, while o3 Deep Research ships a 200k-token context window. On pricing, Gemini 3.1 Pro Preview Custom Tools costs $2/1M input tokens versus $10/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Gemini 3.1 Pro Preview Custom Tools is ~400% cheaper at $2/1M; pay for o3 Deep Research only for reasoning depth.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Pro Preview Custom Tools | o3 Deep Research |
|---|---|---|
| Best for | multimodal apps and long-context analysis | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | RAG, Long context, and Vision | RAG, Agents, and Long context |
| Context window | 1m | 200k |
| Cheapest output | $12/1M tokens | $40/1M tokens |
| Provider routes | 1 tracked | 1 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Gemini 3.1 Pro Preview Custom Tools has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.1 Pro Preview Custom Tools has the lower cheapest tracked output price at $12/1M tokens.
- Local decision data tags Gemini 3.1 Pro Preview Custom Tools for RAG, Long context, and Vision.
- o3 Deep Research uniquely exposes Reasoning, Function calling, and Tool use in local model data.
- Local decision data tags o3 Deep Research for RAG, Agents, and Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Gemini 3.1 Pro Preview Custom Tools
$4,600
Cheapest tracked route/tier: OpenRouter
o3 Deep Research
$18,000
Cheapest tracked route/tier: Vercel AI Gateway
Estimated monthly gap: $13,400. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Gemini 3.1 Pro Preview Custom Tools and o3 Deep Research; plan for SDK, billing, or endpoint changes.
- o3 Deep Research is $28/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- o3 Deep Research adds Reasoning, Function calling, and Tool use in local capability data.
- No overlapping tracked provider route is sourced for o3 Deep Research and Gemini 3.1 Pro Preview Custom Tools; plan for SDK, billing, or endpoint changes.
- Gemini 3.1 Pro Preview Custom Tools is $28/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning, Function calling, and Tool use before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-01-01 | 2025-10-10 |
| Context window | 1m | 200k |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-01 | 2024-06 |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro Preview Custom Tools | o3 Deep Research |
|---|---|---|
| Input price | $2/1M tokens | $10/1M tokens |
| Output price | $12/1M tokens | $40/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3.1 Pro Preview Custom Tools | o3 Deep Research |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| Function calling | No | Yes |
| Tool use | No | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Deep dive
The capability footprint differs most on reasoning mode: o3 Deep Research, function calling: o3 Deep Research, and tool use: o3 Deep Research. Both models share vision, multimodal input, and structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Gemini 3.1 Pro Preview Custom Tools lists $2/1M input and $12/1M output tokens on the cheapest tracked provider, while o3 Deep Research lists $10/1M input and $40/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3.1 Pro Preview Custom Tools lower by about $14 per million blended tokens. Availability is 1 providers versus 1, so concentration risk also matters.
Choose Gemini 3.1 Pro Preview Custom Tools when long-context analysis, larger context windows, and lower input-token cost are central to the workload. Choose o3 Deep Research when reasoning depth are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions.
FAQ
Which has a larger context window, Gemini 3.1 Pro Preview Custom Tools or o3 Deep Research?
Gemini 3.1 Pro Preview Custom Tools supports 1m tokens, while o3 Deep Research supports 200k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Gemini 3.1 Pro Preview Custom Tools or o3 Deep Research?
Gemini 3.1 Pro Preview Custom Tools is cheaper on tracked token pricing. Gemini 3.1 Pro Preview Custom Tools costs $2/1M input and $12/1M output tokens. o3 Deep Research costs $10/1M input and $40/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Gemini 3.1 Pro Preview Custom Tools or o3 Deep Research open source?
Gemini 3.1 Pro Preview Custom Tools is listed under Proprietary. o3 Deep Research is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Gemini 3.1 Pro Preview Custom Tools or o3 Deep Research?
Both Gemini 3.1 Pro Preview Custom Tools and o3 Deep Research expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Gemini 3.1 Pro Preview Custom Tools or o3 Deep Research?
Both Gemini 3.1 Pro Preview Custom Tools and o3 Deep Research expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Gemini 3.1 Pro Preview Custom Tools and o3 Deep Research?
Gemini 3.1 Pro Preview Custom Tools is available on OpenRouter. o3 Deep Research is available on Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-15. Data sourced from public model cards and provider documentation.