# Grok 4.1 Fast (Reasoning)
Next-generation tool-calling agent model optimized for agentic workflows with reasoning capabilities.
## Model Details
| Property | Value |
|----------|-------|
| Model ID | `grok-4-1-fast-reasoning` |
| Context Length | 2,000,000 tokens (2M input + 30K max output) |
| Input Modalities | Text, Images |
| Output Modality | Text |
| Output Speed | 90 characters/second |
| Release Date | November 17, 2025 |
| Elo Rating | #2 at 1465 Elo (reasoning mode) |
## Pricing
| Type | Cost per 1M tokens |
|------|-------------------|
| Input | $0.20 |
| Output | $0.50 |
| Cached | $0.05 |
| Web Search | $5.00 per 1K calls |
## Rate Limits
- 4M tokens/minute
- 480 requests/minute
## Capabilities
- Agentic tool calling optimized for agent workflows
- Text and image input support
- Reasoning enabled with thinking tokens
- Prompt caching support
- Web search integration
- Structured outputs
- Long-horizon reinforcement learning trained
- **50% reduced hallucination rate** compared to Grok 4 Fast
## Supported Parameters
- `reasoning`
- `temperature`
- `top_p`
- `max_tokens`
- `tools`
- `tool_choice`
- `response_format`
- `seed`
- `logprobs`
- `top_logprobs`
- `structured_outputs`
## Usage
```python
from openai import OpenAI
client = OpenAI(
api_key=os.environ.get("XAI_API_KEY"),
base_url="https://api.x.ai/v1"
)
response = client.chat.completions.create(
model="grok-4-1-fast-reasoning",
messages=[
{"role": "user", "content": "Complete this multi-step task"}
],
tools=[...] # Agent tools
)
```
## Notes
- Best model for agentic workflows
- 50% fewer hallucinations than previous generation
- Trained with long-horizon reinforcement learning
- Use for complex multi-step agent tasks
- Available in xAI Enterprise API
