Model capability probe

xAI: Grok 4 | JSON mode

Whether xAI: Grok 4 supports JSON mode cannot be decided from the name alone. Check model ID x-ai/grok-4, provider xAI, catalog params, modality, a lightweight runtime probe, and the error body together.

Model

x-ai/grok-4

xAI: Grok 4

Provider

xAI

10 models in catalog

Capability

JSON mode

json-mode

Catalog signal

catalog shows support

Context: 256,000

Capability probe summary

Model

x-ai/grok-4

Capability

json-mode

Catalog signal

catalog shows support

Read-only check. Detection data burns after 5 minutes.

How to judge this capability

Whether xAI: Grok 4 supports JSON mode cannot be decided from the name alone. Check model ID x-ai/grok-4, provider xAI, catalog params, modality, a lightweight runtime probe, and the error body together.

Model: x-ai/grok-4
Provider: xAI
Capability: JSON mode

How to prove it during checking

Read-only check. Detection data burns after 5 minutes.

Start with the catalog signal: catalog shows support, then verify with a real key in read-only mode.
The capability probe must bind model ID x-ai/grok-4; do not test another model from the same provider.
JSON mode · supports include_reasoning · supports logprobs · supports max_tokens · supports reasoning

Next action

xAI: Grok 4 JSON mode should turn into an operator action: confirm sale tags, fill the capability matrix, change route, suggest a fallback model, or mark unsupported for now.

Read-only check. Detection data burns after 5 minutes.
Catalog signal: catalog shows support
Context: 256,000

Open key checker

Read-only check. Detection data burns after 5 minutes.