Claude Opus 4 & Sonnet 4 System Card

A system card by Anthropic about Claude Opus 4 and Claude Sonnet 4, published 22 May 2025. We recorded 45 values from it.

Developer: Anthropic
Type: System card
Models covered: Claude Opus 4, Claude Sonnet 4
Published: 22 May 2025
Original: The document at www-cdn.anthropic.com (opens an external site)
Also at: Another address, anthropic.com (opens an external site) (redirect)
Archived copy: No archived copy yet
Changelog: Has a changelog

Data as of 26 Sep 2026 · Dataset v0.1 · Methodology v0.1 · Changelog

Versions

Four versions are on record, oldest first. We hold a copy of one; the others are known only by their date.

22 May 2025
First published version
Date from

our source registry
Copy

Known to exist; no copy held
16 Jul 2025
Revision
Date from

the document's changelog
Copy

Known from the changelog; no copy held
What changed footnote and formatting
2 Sep 2025
Revision
Date from

the document's changelog
Copy

Known from the changelog; no copy held
What changed corrected Claude Code Impossible Tasks numbers
26 Sep 2026
Date retrieved
Copy retrieved 26 Sep 2026
Date from

the date we retrieved it; the copy states no version date
Copy

Copy retrieved on 26 Sep 2026
Address

This version at www-cdn.anthropic.com (opens an external site)
Values

45 values recorded from this version

No version has a file hash or an archived snapshot yet. From dataset v0.2 each retrieved version carries both (Methodology §7).

Revisions

No revisions are recorded for this document. Without copies of the earlier versions, changes between them are not recorded value by value; what we know of each version is listed below.

Values

Every value we recorded from this document, grouped by metric family and ordered by where the document prints it. Location is the section, table or page as the document numbers it. 2 of the 45 have been blind-verified: a second reader found the same value without seeing ours.

KeyVerifiedUnverifiedDisputedCorrected read off a figure or stated in wordsA value opens its source and history.

M1 Evaluation awareness

2 values

M1 Evaluation awareness: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Value	Location	Checked
Claude Opus 4	Automated behavioral auditTranscripts flagged for situational awareness	of 414 audit transcripts		Sec 4.1.2.2	Verified
Claude Sonnet 3.7	Automated behavioral auditTranscripts flagged for situational awareness	of 414 audit transcripts		Sec 4.1.2.2	Unverified

M2 Reward hacking

2 values

M2 Reward hacking: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Value	Location	Checked
Claude Opus 4	Reward hacking (hard-coding)Avg decrease in hard-coding vs Sonnet 3.7	vs Sonnet 3.7		Sec 6	Unverified
Claude Sonnet 4	Reward hacking (hard-coding)Avg decrease in hard-coding vs Sonnet 3.7	vs Sonnet 3.7		Sec 6	Unverified

M3 Sabotage and sandbagging

4 values

M3 Sabotage and sandbagging: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Location	Checked
Claude Opus 4	Subtle sabotage (agentic)Side-task success without monitor detection	hidden scratchpad	Table 4.1.10.B	Unverified
Claude Opus 4	Subtle sabotage (agentic)Side-task success without monitor detection	scratchpad visible to monitor	Table 4.1.10.B	Unverified
Claude Sonnet 3.7	Subtle sabotage (agentic)Side-task success without monitor detection	hidden scratchpad	Table 4.1.10.B	Unverified
Claude Sonnet 3.7	Subtle sabotage (agentic)Side-task success without monitor detection	scratchpad visible to monitor	Table 4.1.10.B	Unverified

M4 Misalignment audits

4 values

M4 Misalignment audits: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Location	Checked
Claude Opus 4	Opportunistic blackmail scenarioShare of rollouts with blackmail	replacement model shares values	Sec 4.1.1.2	Unverified
Claude Opus 4	Automated behavioral auditSurprising high-impact actions found	audit transcripts	Sec 4.1.9	Unverified
Claude Sonnet 3.7	Automated behavioral auditSurprising high-impact actions found	audit transcripts	Sec 4.1.9	Unverified
Claude Sonnet 4	Automated behavioral auditSurprising high-impact actions found	audit transcripts	Sec 4.1.9	Verified

M5 Honesty and hallucination

4 values

M5 Honesty and hallucination: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Location	Checked
Claude Opus 4	Reasoning-behavior monitorKnowingly hallucinated information	RL-style transcripts	Table 4.1.6.A	Unverified
Claude Opus 4	Reasoning-behavior monitorOutputs showing deception (overall)	RL-style transcripts	Table 4.1.6.A	Unverified
Claude Sonnet 3.7	Reasoning-behavior monitorKnowingly hallucinated information	RL-style transcripts	Table 4.1.6.A	Unverified
Claude Sonnet 3.7	Reasoning-behavior monitorOutputs showing deception (overall)	RL-style transcripts	Table 4.1.6.A	Unverified

M6 Sycophancy

2 values

M6 Sycophancy: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Value	Location	Checked
Claude Opus 4	Reasoning-behavior monitorOutputs showing sycophancy	RL-style transcripts		Table 4.1.6.A	Unverified
Claude Sonnet 3.7	Reasoning-behavior monitorOutputs showing sycophancy	RL-style transcripts		Table 4.1.6.A	Unverified

M7 Harmful compliance and over-refusal

12 values

M7 Harmful compliance and over-refusal: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Location	Checked
Claude Opus 4	Single-turn violative requestsHarmless response rate	extended thinking	Table 2.1.A	Unverified
Claude Opus 4	Single-turn violative requestsHarmless response rate	no extended thinking	Table 2.1.A	Unverified
Claude Opus 4	Single-turn violative requestsHarmless response rate	overall across thinking modes	Table 2.1.A	Unverified
Claude Opus 4	Single-turn violative requestsHarmless response rate	overall across thinking modes; with ASL-3 safeguards	Table 2.1.A	Unverified
Claude Sonnet 3.7	Single-turn violative requestsHarmless response rate	overall across thinking modes	Table 2.1.A	Unverified
Claude Sonnet 4	Single-turn violative requestsHarmless response rate	overall across thinking modes	Table 2.1.A	Unverified
Claude Opus 4	Single-turn benign requestsOver-refusal rate	overall across thinking modes	Table 2.2.A	Unverified
Claude Sonnet 3.7	Single-turn benign requestsOver-refusal rate	overall across thinking modes	Table 2.2.A	Unverified
Claude Sonnet 4	Single-turn benign requestsOver-refusal rate	overall across thinking modes	Table 2.2.A	Unverified
Claude Opus 4	Malicious agentic codingSafety score	without safeguards	Table 3.3.A	Unverified
Claude Sonnet 3.7	Malicious agentic codingSafety score	without safeguards	Table 3.3.A	Unverified
Claude Sonnet 4	Malicious agentic codingSafety score	without safeguards	Table 3.3.A	Unverified

M8 Jailbreak robustness

6 values

M8 Jailbreak robustness: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Location	Checked
Claude Opus 4	StrongREJECTBest-jailbreak StrongREJECT score	extended thinking	Table 2.7.A	Unverified
Claude Opus 4	StrongREJECTBest-jailbreak StrongREJECT score	no extended thinking	Table 2.7.A	Unverified
Claude Sonnet 3.7	StrongREJECTBest-jailbreak StrongREJECT score	extended thinking	Table 2.7.A	Unverified
Claude Sonnet 3.7	StrongREJECTBest-jailbreak StrongREJECT score	no extended thinking	Table 2.7.A	Unverified
Claude Sonnet 4	StrongREJECTBest-jailbreak StrongREJECT score	extended thinking	Table 2.7.A	Unverified
Claude Sonnet 4	StrongREJECTBest-jailbreak StrongREJECT score	no extended thinking	Table 2.7.A	Unverified

M9 Prompt injection

6 values

M9 Prompt injection: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Location	Checked
Claude Opus 4	Computer-use prompt injectionAttack prevention rate	with safeguards	Table 3.2.A	Unverified
Claude Opus 4	Computer-use prompt injectionAttack prevention rate	without safeguards	Table 3.2.A	Unverified
Claude Sonnet 3.7	Computer-use prompt injectionAttack prevention rate	with safeguards	Table 3.2.A	Unverified
Claude Sonnet 3.7	Computer-use prompt injectionAttack prevention rate	without safeguards	Table 3.2.A	Unverified
Claude Sonnet 4	Computer-use prompt injectionAttack prevention rate	with safeguards	Table 3.2.A	Unverified
Claude Sonnet 4	Computer-use prompt injectionAttack prevention rate	without safeguards	Table 3.2.A	Unverified

M10 Dangerous capabilities and risk determinations

3 values

M10 Dangerous capabilities and risk determinations: values in the Claude Opus 4 & Sonnet 4 System Card
Model	Evaluation	Condition	Location	Checked
Claude Opus 4	RSP deployment standardASL standard deployed under	None stated	Sec 1 / Sec 7	Unverified
Claude Sonnet 4	RSP deployment standardASL standard deployed under	None stated	Sec 1 / Sec 7	Unverified
Claude Opus 4	CybenchCTF challenges solved	of 39 challenges	Sec 7.4	Unverified

Extraction coverage

What we read of this document, and where each value was read.

Our note Web reader stopped at §4.2.1; later sections partly from secondary write-ups

Of the 45 values, 42 were read in the document itself and 3 in independent write-ups that quote it.

Values read somewhere other than the document stand in where the document's own section could not be read directly, and are flagged on every value (Methodology §2.2).

Independent write-ups used

Simon Willison’s weblog (opens an external site) · 2 values
The Stack (opens an external site) · 1 value

All 45 values were extracted for version 0 of the dataset through a web reader, which did not always reach the later sections of long PDFs (Methodology §3).

Where next

AnthropicEvery Anthropic document, model and changelog practice
Claude Opus 4Every value about this model, from every document
Claude Sonnet 4Every value about this model, from every document
All documentsEvery document by developer and date
Revisions ledgerEvery recorded change to a document, newest first
M1 · Evaluation awarenessThis family across every developer and document
M2 · Reward hackingThis family across every developer and document
M3 · Sabotage and sandbaggingThis family across every developer and document
M4 · Misalignment auditsThis family across every developer and document
M5 · Honesty and hallucinationThis family across every developer and document
M6 · SycophancyThis family across every developer and document
M7 · Harmful compliance and over-refusalThis family across every developer and document
M8 · Jailbreak robustnessThis family across every developer and document
M9 · Prompt injectionThis family across every developer and document
M10 · Dangerous capabilities and risk determinationsThis family across every developer and document