Gemini 3.1 Pro Preview Custom Tools vs Phi-4 Mini Reasoning
Gemini 3.1 Pro Preview Custom Tools (2026) and Phi-4 Mini Reasoning (2026) are frontier reasoning models from Google DeepMind and Microsoft Research. Gemini 3.1 Pro Preview Custom Tools ships a 1M-token context window, while Phi-4 Mini Reasoning ships a 128K-token context window. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
Gemini 3.1 Pro Preview Custom Tools fits 8x more tokens; pick it for long-context work and Phi-4 Mini Reasoning for tighter calls.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Pro Preview Custom Tools | Phi-4 Mini Reasoning |
|---|---|---|
| Best for | long-context analysis | reasoning-heavy apps |
| Decision fit | RAG, Long context, and Classification | Long context |
| Context window | 1M | 128K |
| Cheapest output | $12/1M tokens | - |
| Provider routes | 1 tracked | 0 tracked |
| Shared benchmarks | 0 rows | 0 rows |
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 broader tracked provider coverage for fallback and procurement flexibility.
- Gemini 3.1 Pro Preview Custom Tools uniquely exposes Structured outputs in local model data.
- Local decision data tags Gemini 3.1 Pro Preview Custom Tools for RAG, Long context, and Classification.
- Phi-4 Mini Reasoning uniquely exposes Reasoning in local model data.
- Local decision data tags Phi-4 Mini Reasoning for 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
Phi-4 Mini Reasoning
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Gemini 3.1 Pro Preview Custom Tools and Phi-4 Mini Reasoning; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Structured outputs before moving production traffic.
- Phi-4 Mini Reasoning adds Reasoning in local capability data.
- No overlapping tracked provider route is sourced for Phi-4 Mini Reasoning and Gemini 3.1 Pro Preview Custom Tools; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Reasoning before moving production traffic.
- Gemini 3.1 Pro Preview Custom Tools adds Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-01-01 | 2026-05-16 |
| Context window | 1M | 128K |
| Parameters | — | 3.8B |
| Architecture | decoder only | - |
| License | Unknown | Proprietary |
| Knowledge cutoff | 2025-01 | 2025-02 |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro Preview Custom Tools | Phi-4 Mini Reasoning |
|---|---|---|
| Input price | $2/1M tokens | - |
| Output price | $12/1M tokens | - |
| Providers | - |
Capabilities
| Capability | Gemini 3.1 Pro Preview Custom Tools | Phi-4 Mini Reasoning |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | No | Yes |
| Function calling | No | No |
| Tool use | No | No |
| Structured outputs | Yes | No |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on reasoning mode: Phi-4 Mini Reasoning and structured outputs: Gemini 3.1 Pro Preview Custom Tools. Both models share the core language-model surface, 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.
Pricing coverage is uneven: Gemini 3.1 Pro Preview Custom Tools has $2/1M input tokens and Phi-4 Mini Reasoning has no token price sourced yet. Provider availability is 1 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Gemini 3.1 Pro Preview Custom Tools when long-context analysis, larger context windows, and broader provider choice are central to the workload. Choose Phi-4 Mini Reasoning 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. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, Gemini 3.1 Pro Preview Custom Tools or Phi-4 Mini Reasoning?
Gemini 3.1 Pro Preview Custom Tools supports 1M tokens, while Phi-4 Mini Reasoning supports 128K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Gemini 3.1 Pro Preview Custom Tools or Phi-4 Mini Reasoning open source?
Gemini 3.1 Pro Preview Custom Tools is listed under Unknown. Phi-4 Mini Reasoning 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 reasoning mode, Gemini 3.1 Pro Preview Custom Tools or Phi-4 Mini Reasoning?
Phi-4 Mini Reasoning has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for structured outputs, Gemini 3.1 Pro Preview Custom Tools or Phi-4 Mini Reasoning?
Gemini 3.1 Pro Preview Custom Tools has the clearer documented structured outputs signal in this comparison. If structured outputs is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Gemini 3.1 Pro Preview Custom Tools and Phi-4 Mini Reasoning?
Gemini 3.1 Pro Preview Custom Tools is available on OpenRouter. Phi-4 Mini Reasoning is available on the tracked providers still being sourced. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
When should I pick Gemini 3.1 Pro Preview Custom Tools over Phi-4 Mini Reasoning?
Gemini 3.1 Pro Preview Custom Tools fits 8x more tokens; pick it for long-context work and Phi-4 Mini Reasoning for tighter calls. If your workload also depends on long-context analysis, start with Gemini 3.1 Pro Preview Custom Tools; if it depends on reasoning depth, run the same evaluation with Phi-4 Mini Reasoning.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.