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x-AI/Grok-4.1-Fast

Reasoning Tool Calling

Grok 4.1 Fast is xAI's best agentic tool calling model that shines in real-world use cases like customer support and deep research. 2M context window. Reasoning can be enabled/disabled using the `reasoning` `enabled` parameter in the API. [Learn more in our docs](https://openrouter.ai/docs/use-cases/reasoning-tokens#controlling-reasoning-tokens)

Providers 1
Released Nov 20, 2025
Input Modalities text
Output Modalities text
Tarsk Use coding

Benchmarks

23.6
Intelligence Index
19.5
Coding Index
34.3
Math Index

Available Providers (1)

Provider Model ID Input Cost Output Cost Context Max Output Docs
Qiniu x-ai/grok-4.1-fast —/MTok —/MTok 2M 2M

Capabilities

Reasoning
Tool Calling
Attachments
Open Weights
Structured Output