Claude Sonnet 4.6 vs Grok 4 for Faithfulness

What Faithfulness demands: remaining strictly tied to source material, avoiding invented facts, accurately citing or mapping sources, and refusing to fabricate when evidence is missing. Capabilities that matter most: safety_calibration (refusal/guardrails), tool_calling (correct function selection and argument accuracy for retrieval), structured_output (schema adherence for verifiable outputs), long_context (retrieval across large documents), and persona_consistency (avoids injecting new claims). In our testing both models earn the top faithfulness score (taskScore: 5 for Claude Sonnet 4.6 and 5 for Grok 4), so the primary metric ties. To break the tie we inspect supporting proxies: Claude Sonnet 4.6 has safety_calibration 5 vs Grok 4's 2, and tool_calling 5 vs Grok 4's 4 — both favor Sonnet for fewer hallucinations and more reliable retrieval/tool use. Claude Sonnet 4.6 also reports external results on third‑party tests: 75.2% on SWE-bench Verified and 85.8% on AIME 2025 (Epoch AI), which we cite as supplementary evidence; Grok 4 has no external benchmark scores in the payload. Grok 4’s advantages relevant to faithfulness are a stronger constrained_rewriting score (4 vs 3) and adequate long_context (both 5), which help when producing compressed, faithful summaries under tight length limits.

Where Claude Sonnet 4.6 shines for Faithfulness:

• Automated citation pipelines: Sonnet’s tool_calling 5 vs Grok 4 means it’s less likely to mis-route retrieval tools or pass incorrect arguments when assembling source-backed answers. Use it when you must fetch exact lines or commit hashes and annotate them.
• High-risk content gating: With safety_calibration 5 vs Grok’s 2, Sonnet better refuses to answer when source evidence is missing, reducing hallucinated claims for legal, medical, or compliance outputs.
• Long-document fidelity: Sonnet’s long_context 5 and structured_output 4 support faithful extraction and JSON-schema outputs for downstream verification. Where Grok 4 shines for Faithfulness:
• Constrained publishing: Grok’s constrained_rewriting 4 vs Sonnet 3 makes it better at compressing source material into strict character/space budgets while preserving accuracy.
• Large-context retrieval parity: Grok also has long_context 5, so for very large documents it matches Sonnet on retrieval-based fidelity.
• Cost and tooling parity: Both models list the same input/output mTok costs (3 and 15), so choose Grok when constrained rewriting under tight length limits is the primary need and you can accept lower safety calibration.

For Faithfulness, choose Claude Sonnet 4.6 if you need conservative, source-anchored answers with stronger safety and tool-calling (Safer refusals, fewer hallucinations). Choose Grok 4 if your primary requirement is faithful compression into tight limits (higher constrained_rewriting) and you can accept weaker safety calibration.