GPT-5.4 vs Grok 4 for Faithfulness

What Faithfulness demands: accuracy to source text, faithful extraction or summarization, minimal hallucination, robust refusals on unsupported claims, consistent structured outputs, and correct tool or database use when retrieving facts. In our absence of an external benchmark for this task, the primary evidence is our internal faithfulness score: both models received 5/5 and share rank 1 of 52. To explain practical differences we examine supporting proxies from our 12-test suite: GPT-5.4 scores 5/5 on safety calibration and 5/5 on structured output, plus a 1,050,000-token context window and max output tokens of 128,000—advantages for long-source fidelity and strict schema adherence. Grok 4 matches GPT-5.4 on faithfulness (5/5), tool calling (4/5), strategic analysis (5/5) and long context (5/5), but scores 2/5 on safety calibration and 4/5 on structured output. Those internal scores indicate both models can be faithful in controlled prompts, but GPT-5.4 is stronger where refusal behavior, schema compliance, and multi-hundred-thousand-token context matter.

Where GPT-5.4 shines: 1) Summarizing or extracting clauses from a 200k‑token legal corpus while emitting strict JSON — GPT-5.4's structured output 5/5 and 1,050,000-token context reduce truncation and format errors. 2) Producing source-cited research summaries that must refuse invented citations — its safety calibration 5/5 helps resist hallucination. 3) Long-form reconciliation across many documents where cost-sensitive input streaming matters (input cost 2.5 vs Grok’s 3 per mTok). Where Grok 4 shines: 1) Classification-first pipelines or routing where Grok’s classification score (4/5 vs GPT-5.4’s 3/5) and tied faithfulness mean faster integration into label-driven tooling. 2) Compact reasoning tasks that require parity on strategic analysis and tool calling (both score 5 and 4 respectively in our tests). Caveats from our tests: Grok 4’s safety calibration is 2/5 in our suite, so in adversarial or ambiguous prompts it was less likely to apply conservative refusals compared with GPT-5.4.

For Faithfulness, choose GPT-5.4 if you need best-in-class refusal behavior, strict schema compliance, or fidelity over very long contexts (safety calibration 5 vs 2; structured output 5 vs 4; 1,050,000 vs 256,000 token context). Choose Grok 4 if you need a model that ties on faithfulness in direct tests but prioritizes stronger classification (4 vs 3) or fits workflows that already compensate for weaker safety calibration.