Anthropic introduced Claude Mods for Claude Code. A mod is a plugin that runs TypeScript or JavaScript inside the tool. Mods respond to events like prompts, tool calls or interface renders. They can change how events are shown or handled. Anthropic ships six built-in mods including one that flags missed details. Users can also ask Claude Code to build a mod for them. Mods are not sandboxed and can read files, see prompts and spend usage. They add cost because each check re-reads the conversation. Mods can be turned off with a command. The goal is to let users shape how the agent asks for human attention.