GPT-5.1 vs GPT-5 Mini

1. Configurable Reasoning for Agentic Tasks

• Built to excel in autonomous or semi-autonomous coding workflows, with adjustable reasoning effort for planning, refactoring and debugging.

2. Fast Multi-Modal Input with Large Output

• Accepts both text and image inputs while producing text outputs.
• Offers up to 128 k output tokens, allowing long responses and code generation across multiple files.

3. Large Context & Knowledge Cut-Off

• 400 k token context window supports processing large codebases or documents.
• Knowledge cut-off of Sep 30 2024 ensures familiarity with recent tools and frameworks.

4. Reasoning Token Support

• Provides explicit support for reasoning tokens, enabling developers to fine-tune the balance between reasoning depth and speed.

1. High reasoning performance

• Retains strong reasoning capabilities despite being a smaller, faster model.
• Suitable for tasks requiring accurate logic and structured thinking.

2. Fast and cost-efficient

• Optimized for speed, making it ideal for real-time or high-volume workloads.
• Far cheaper than GPT-5 while maintaining solid capability.

3. Great for well-defined tasks

• Excels when prompts are precise and objectives are clearly specified.
• More predictable and stable for deterministic workflows.

4. Multimodal input

• Accepts text + image as input.
• Outputs text only.

5. Tool support

• Works with Web Search, File Search, Code Interpreter, MCP.
• (Does not support Image Generation as a tool and does not support Computer Use.)