xAI / Grok

Use the xai provider for xAI Grok models. xAI supports both web_search and x_search; fast-agent sends x_search as xAI's provider-managed X Search tool.

Configure

xai:
  api_key: "${XAI_API_KEY}"
  # base_url: "https://api.x.ai/v1" # default

Environment variables:

• XAI_API_KEY: Your xAI API key
• XAI_BASE_URL: Override the API endpoint

Use a model

fast-agent --model grok
fast-agent --model "xai.grok-4.3?reasoning=high"
fast-agent --model "xai.grok-4.3?web_search=on"
fast-agent --model "xai.grok-4.3?x_search=on"

Reasoning and search tools

Useful xAI query parameters:

• reasoning=none|low|medium|high on reasoning-capable Grok models
• web_search=on|off for xAI web search
• x_search=on|off for xAI's X Search remote tool

web_search and x_search are distinct provider-managed tools.

Capabilities

Capabilities are model-dependent. See Models Reference for fast-agent's known structured output, reasoning, modality, and tool metadata.

Model aliases