When AI Writes 65% of the Code: Counterintuitive Prompt Engineering Truths from Inside Anthropic
Anthropic's team reveals that Claude Tag now lands 65% of engineering PRs, cutting system prompts by 80% improves results with new models, and negative instructions can degrade output quality.
Simon Willison · Jul 21, 2026
How I tricked Claude into leaking your deepest, darkest secrets
A researcher found a loophole in Claude's web_fetch tool that allowed attackers to exfiltrate private data letter by letter via a honeypot site, highlighting new challenges in AI智能体 security.
Simon Willison · Jul 15, 2026
What's new in Claude Sonnet 5
Claude Sonnet 5 brings Opus-level performance at Sonnet prices, but a tokenizer change effectively raises costs by 30% for English users; removed sampling params and default thinking mode add more hidden costs.
Simon Willison · Jul 1, 2026
The Fable 5 Export Controls Harm US Cyber Defense
The US export controls on Claude Fable 5 for being able to 'fix code' misunderstand that this is a normal defensive security activity, and such controls harm rather than help cybersecurity.
Simon Willison · Jun 16, 2026
An update on our election safeguards
Anthropic reveals its use of constitutional training, system prompts, and published evaluation datasets to keep Claude politically neutral, while coupling them with policy enforcement to prevent election abuse—reflecting a broader shift of AI companies into information governance roles.
Anthropic News · Jun 6, 2026
Government of Alberta uses Claude to find and fix cybersecurity vulnerabilities across government systems
The Government of Alberta used 50 Claude Code agents to scan 466 million lines of code in 20 hours, finding and fixing security vulnerabilities and compressing years of audit work into a single day.
Anthropic News ·
Introducing a way to reflect on how you use Claude
Anthropic launches a reflection dashboard to help users track and shape how they use Claude, introducing the 4D AI Fluency Framework to promote mindful AI collaboration.
Anthropic News ·
UST is bringing Claude to physical AI
UST integrates Claude into physical engineering workflows like chip validation, achieving 50-70% efficiency gains and marking a significant step of AI into the physical economy.
Anthropic News ·
Introducing the Services Track and Partner Hub of the Claude Partner Network
Anthropic launches a tiered Services Track and a transparent Partner Hub for its Claude Partner Network, shifting the AI ecosystem's focus from model capability to delivery quality and trust.
Anthropic News ·
Introducing Claude Sonnet 5
Anthropic's Sonnet 5 delivers agentic performance close to the Opus flagship at significantly lower cost, enabling developers to build powerful autonomous agents with mid-tier models.
Anthropic News ·