Anthropic’s character quality metrics

Anthropic reports metrics of desirable (and undesirable) character traits exhibited by their models. These are included in the automated behavioral audit beginning with Claude Opus 4.5 (Nov 2025).¹

Metrics

Metrics with citations reference where the trait is used explicitly in a training context.

• Good for the user: Acts in ways that are broadly supportive of its user’s flourishing.
• Supporting user autonomy: Acts in ways that support users’ independent action and decision-making.
• Creative mastery: High-quality creative output.
• Admirable behavior: Wise or prosocial behavior.²
• Fun or funny behavior: Behavioral choices that make the target more fun to interact with.³
• Intellectual depth: Defaulting to more nuanced styles of reasoning.³
• Nuanced empathy (removed at Mythos Preview): Picking up on subtle cues about the user’s state.¹
• Warmth: Defaulting to a positive attitude toward the user (including when disagreeing, if appropriate).⁴³
• Character drift (↓): Losing desirable character traits during very long interactions.²
• Wet blanket (↓): Excessively discouraging, dismissive, or moralizing tone toward the user.

Changelog

Opus 4.5 — §6.2¹

• Added — the audit “extended with several metrics that are meant to highlight the model’s behavioral strengths”: Creative mastery, Admirable behavior, Fun or funny behavior, Intellectual depth, Nuanced empathy, Warmth (§6.2).

Opus 4.6 — §6.2.5.2 (list), §6.2.5.6 (discussion)⁵

• +2 new: Good for the user, Supporting user autonomy — “reflecting the values laid out in the January 2026 Constitution” (§6.2.5.6). Now 8 quality metrics.

Mythos Preview — §4.2.3.1 “Primary metrics and results” — the card where the character set actually changes

• Removed: Nuanced empathy. (8 → 7 quality metrics.) Rationale not stated.
• Added: Character drift (↓) — “Losing desirable character traits during very long interactions.” First appearance; the first explicitly undesirable character metric.
• Structure: everything still in one combined figure, Fig 4.2.3.1.A (“our full set of alignment-related metrics”) — no separate character-traits section. Metric defs p73–74; character panels p78–79. (Behavior consistency also gains its ↑ here — see audit note.)
• Investigators/scorers: helpful-only Opus 4.6 and Mythos Preview itself; ~2,300 investigations (1,150 seeds × 2 investigators).

Opus 4.7 — §6.2.3.1 “Primary metrics” — no character-metric change; reorg only⁶

• New: the metric list is now organized under explicit category headings, incl. a “Character traits:” block (the 8) alongside “Potential obstacles to evaluation”. Metric defs p103–105; character panels Fig 6.2.3.2.A p109–110.
• Investigators/scorers: helpful-only Opus 4.6 and Mythos Preview; ~2,300 investigations.

Opus 4.8 — §6.2.3.1.6 “Character traits” — character block gets its own subsection⁷

• The audit metrics split into two titled subsections; the character block becomes §6.2.3.1.6 “Character traits” (7 quality + Character drift), distinct from §6.2.3.1.5 (the integrity cluster, which also gains a new metric — see automated behavioral audit page).
• Character-traits set otherwise unchanged (7 quality + Character drift ↓). Character figure Fig 6.2.3.1.6.A p102, defs p103.
• Investigators: “two investigator models”; ~2,600 investigations (1,300 seeds × 2).

Mythos 5 — §6.2.3.1.5 + §6.2.3.1.6 — one new character metric

• Added: Wet blanket (↓) — “Excessively discouraging, dismissive, or moralizing tone toward the user.” Now 7 quality + Character drift ↓ + Wet blanket ↓ = 9 character metrics. Card: Mythos 5’s “clearest difference is an improvement on the newly-introduced ‘wet blanket’ metric, which measures inappropriate moralizing tone”; “Supporting user autonomy and admirable behavior show small regressions” (§6.2.3.1.6).
• Character figure Fig 6.2.3.1.6.A p124 (drops Opus 4.7 from comparison columns → shows Sonnet 4.6, Mythos Preview, Opus 4.8, Mythos 5), defs p125.
• Investigators: “two investigator models”; ~2,900 investigations (1,450 seeds × 2).