Grok 4.1 Fast (Reasoning)
xAI's fast agentic tool-calling model with a 2M context window and built-in reasoning
BENCHMARKS
Not in the Epoch Capabilities Index. Epoch benchmarks what it can run, so this is a gap in coverage, not a poor result.
RELEASE DATENov 19, 2025
WEIGHTSClosed weights
CONTEXT WINDOW2M
MAX OUTPUT30K
REASONINGYes
TOOL CALLINGYes
INPUTStext, image
OUTPUTStext
Specifications from Models.dev. Availability and limits may differ by provider. Benchmark scores come from Epoch AI under CC BY 4.0.