Model Cards / Anthropic

Claude Sonnet 5 System Card

model card34,762 words·151 min read·Aug 3, 2026·Source
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Summary
34,762-word document condensed to 175 words. Anthropic · Aug 3, 2026
TL;DR

This system card describes Claude Sonnet 5, the latest model in Anthropic’s Sonnet family. It is an upgrade to Claude Sonnet 4.6, with gains in various aspects of agentic performance.

Top benchmarks
BenchmarkVariantScore
DNA Synthesis Screening Evasion5.0%
Long-form virology taskstask_182.0%
Long-form virology taskstask_179.0%
VCT56.0%
VCT50.0%
VCT47.0%
VCT45.0%
VCT22.1%

Showing top 8 of 58. See full list below.

Safety findings
  • We believe these mitigations make catastrophic risk in this category low but still not negligible, for reasons discussed in our most recent Risk Report .
  • We believe these risk mitigations are equal to or stronger than our historical ASL-3 protections and sufficient to make catastrophic risk in this category very low but not negligible (further discussion of our reasoning can be found in our most recent Risk Report) .
  • We believe Sonnet 5 does not change the picture presented for this threat model in our most recent Risk Report .
Deployment scope
  • available through other widely used models and tools.
What’s new
  • Added a footnote in 8.9.2 BrowseComp with a reproduction recipe via public Messages API. 2

Every italicized passage is a verbatim substring of the source document (checked deterministically after extraction). Field selection is heuristic — some quotes may lack surrounding context and some claims may be absent if no matching pattern appeared. For citation, open the source: original model card · source SHA 7b6f526a27ff · version dated Aug 3, 2026.

Extracted Evaluations(58 results)

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Long-form virology tasks/ task_1
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Long-form virology tasks/ task_1
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BenchCAD
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Terminal-Bench/ 2.1
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FrontierCode
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CursorBench
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USAMO/ 2026
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ArxivMath
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ProgramBench
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GDP.pdf
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ChartMuseum
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CharXiv/ reasoning
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Legal Agent Benchmark
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Toolathlon
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AutomationBench
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MILU
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INCLUDE
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BioMysteryBench
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LatchBio Bioinformatics
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Structural Biology/ open_ended
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ProteinGym/ hard
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Organic Chemistry
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LinuxArena
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OSS-Fuzz
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Firefox 147
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Long-form virology tasks/ task_2
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Black-box RNA Sequence Design
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Black-box RNA Sequence Design
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Black-box RNA Sequence Design
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Black-box RNA Sequence Design
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Black-box RNA Sequence Design
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AAV_Capsid_Packaging_Prediction
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