A plugin is an add-on that extends Claude Code, and a marketplace is a catalogue that offers plugins to install. Claude Code now checks plugin names for ones that could be mistaken for Anthropic's own. These names give an error:
- Names starting with
claude-,anthropic-,anthropics-orcc-plugin- - The names
claude-codeandclaude-mods - Names that put "official" next to claude or anthropic
Names that look similar in looser ways give a warning instead. The check runs when a marketplace is validated, on a plugin's own plugin.json file, and in the plugin validate command. In the release-tagging command, a plugin is only treated as Anthropic's own if its marketplace passes the Anthropic check. The error message also says that Claude Code refuses a plugin with such a name when it is loaded from a path, for example with --plugin-dir.
Authors of other marketplaces can now get hard errors for plugin names that resemble Anthropic's. If you publish plugins, rename any whose name starts with one of these prefixes.
It is not clear whether installing a plugin from a marketplace also enforces this, or only validation, tagging and loading from a path.