Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.64 Home All releases olderv2.1.63 v2.1.66newer
Claude Code v2.1.64

Built-in Plugins

What

Introduces the concept of built-in plugins that ship with Claude Code and cannot be uninstalled or updated by users.

Details
  • Built-in plugins are identified by the @builtin source suffix
  • They can be enabled or disabled via user settings but not removed
  • Attempting to update or uninstall shows: "Built-in plugins cannot be updated or uninstalled."
  • Built-in plugins can provide skills, hooks, and MCP servers just like regular plugins
Evidence

Built-in plugin system (search for "Built-in plugin", "@builtin", "Built-in plugins cannot be updated or uninstalled")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.64 →