Grok 4.20 Reasoning (Vertex AI (OpenAI-compatible))

Grok 4.20 Reasoning is a closed-weights, reasoning-focused variant in xAI's Grok family, identified by the underlying model id "grok-4-20-0309-reasoning" and surfaced through a Vertex AI OpenAI-compatible endpoint via a third-party gateway. It sits in the broader Grok 4.x lineage alongside faster, non-reasoning siblings and later releases, distinguishing itself by emphasizing deliberative, multi-step problem solving rather than low-latency throughput. The cataloged capability set mirrors that positioning, exposing explicit reasoning control with selectable effort levels, tool use for external actions, structured output for machine-readable responses, temperature tuning, and attachment handling for mixed-context workflows.

In practical terms, the model is aimed at analytical, mathematical, coding, and planning tasks where stepping through intermediate reasoning improves answer quality, and it accepts both text and image inputs while returning text outputs through a very large that quick-info value window. It is intended for workflows that benefit from extended reasoning traces, tool-augmented agents, and image-conditioned prompts, making it a reasonable fit for complex research assistance, code review, and structured data extraction pipelines rather than quick-turn chat or cheap high-volume batch use.