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    grok-4-fast-reasoning

    grok/grok-4-fast-reasoning

    ChatToolsSystem promptReasoning

    Context

    2M

    Max output

    64K

    Input / 1M

    $0.25

    Output / 1M

    $0.60

    Modality

    Chat

    Cutoff

    Oct 2023

    About this model

    Grok-4 Fast Reasoning – optimized for quick structured reasoning and planning tasks

    Best suited for

    • Multi-step problem solving, analytical code debugging, complex logical reasoning, and tasks requiring traceable chain-of-thought before final output.

    Built-in tools

    Gtwy web search

    Hosted by the gateway — enable them per request without wiring your own endpoint.

    Capabilities

    Tools

    Native function calling, so agents can invoke your endpoints.

    System prompt

    Honours a dedicated system role, separate from the user turn.

    Reasoning

    Emits a separate thinking pass before the answer.

    Supported parameters

    creativity_level

    Controls the creativity of responses. Higher values (e.g., 0.7) increase creativity; lower values (e.g., 0.2) make responses more predictable.

    max_tokensMax Tokens Limit

    Specifies the maximum number of text units (tokens) allowed in a response, limiting its length.

    tools

    Lists tool definitions or capabilities available to the model.

    tool_choice

    Decides whether to use tools or just the model for generating responses.

    response_type

    Defines the format or type of the generated response.

    parallel_tool_calls

    Enables parallel execution of tools, allowing multiple tools to run simultaneously.

    reasoning

    Controls the level of reasoning used by the model.

    stream

    Sends the response in real-time as it's being generated.