Fireside Chat with Cat Wu and Thariq Shihipar from the Claude Code Team
Anthropic
During the conversation, they discussed how Claude Code, Claude Tag, and Fable are changing development: Claude Tag closes 65% of PRs for Anthropic's product team, and Claude Code's system prompt has been reduced by 80% for new models. The developers talked about engineers shifting skills toward business acumen, the benefit of rewriting code, and how internal "dogfooding" helps select features based on user retention.
At the AI Engineer World’s Fair, Simon Willison spoke with Cat Wu and Thariq Shihipar from the Claude Code team. They revealed that Claude Tag, a new Slack extension for collaboration, already handles 65% of all product engineering pull requests at Anthropic. Thanks to new models like Fable 5, Claude Code’s system prompt has been reduced by 80%, and prohibition lists ("don't do X") now degrade quality. Developers have noticed that engineers are increasingly delegating routine tasks to AI and focusing on product and business meaning. Thariq noted that rewriting code has become good practice rather than taboo—for example, Bun was rewritten in Rust. Claude Tag acts proactively: it monitors channels, remembers preferences, and can fix bugs on its own. For non-programmers, it serves as a company search engine: marketing uses it to ask questions about features. The team makes feature decisions based on internal "dogfooding": they first launch within Anthropic, monitor active user retention, and only then release externally.
Source: Simon Willison —
original