Gemini 3.1 Pro Preview Custom Tools vs Gemini 3.5 Flash
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for Gemini 3.1 Pro Preview Custom Tools and Gemini 3.5 Flash.
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 3.5 Flash
Gemini 3.5 Flash is Google's high-efficiency multimodal model, bringing near-Pro level coding and reasoning at Flash-tier cost and speed. It is highly optimized for coding proficiency and parallel agentic execution...
Technical Specifications
| Specification | Gemini 3.1 Pro Preview Custom Tools | Gemini 3.5 Flash |
|---|---|---|
| Provider | ||
| Context Window | 1,048,756 tokens | 1,048,576 tokens |
| Agent Suitability | N/A | 88/100 |
| Time to First Token (TTFT) | N/A | 200 ms |
| Deployment Model | managed api | managed api |
| Production Stability | beta | stable |
| API Available | Yes | Yes |
| Released Date | 2026-02-25 | 2026-05-19 |
API Pricing Comparison
Input Price per Million Tokens
Gemini 3.1 Pro Preview Custom Tools
$2.00
Gemini 3.5 Flash
$1.50
Output Price per Million Tokens
Gemini 3.1 Pro Preview Custom Tools
$12.00
Gemini 3.5 Flash
$9.00
Want to test both models live?
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Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
Gemini 3.1 Pro Preview Custom Tools Quirks & Gotchas
No developer gotchas reported.
Gemini 3.5 Flash Quirks & Gotchas
- ▸Excellent multimodal performance — native video understanding
- ▸Tool calling via Google's native function_declarations in Vertex AI