Anthropic expands Claude Cowork with plugins and slashes Claude Code system prompt by 80%

Anthropic announced that its Claude Cowork platform now supports the plugin extension bundle format originally used in Claude Code. The company released a set of knowledge‑work plugins—including commands, agents, hooks and connector definitions—along with a customizer that lets organizations tailor placeholder settings such as chat, email and cloud storage.

In a separate update, Anthropic removed more than 80% of the system prompt used by Claude Code for the Claude Opus 5 and Fable 5 models. The company reported no measurable regression on coding evaluations, attributing previous performance issues to overly‑constraining rules in the prompt. The change encourages developers to simplify prompt engineering and rely on the model’s built‑in reasoning capabilities.