Plugins, explained by monkey

A plugin is one folder that installs a bundle of things into Claude Code in one go: skills (which you can also run as /commands), subagents, hooks, MCP servers and a few other parts. You get plugins from a marketplace, which is just a catalog file in a GitHub repo, not a store. And you manage all of it from one panel, /plugin.

Copy-paste setup: your first plugin

Inside a Claude Code session. Anthropic's official marketplace, claude-plugins-official, is already added the first time you start Claude Code, so you can install from it straight away:

/plugin                                                 # open the panel
/plugin install commit-commands@claude-plugins-official # opens its details page
/reload-plugins                                         # apply, if the panel didn't

The install line doesn't install yet. Inside a session it opens the plugin's details page, so you can read what's in it, check its context cost and pick a scope. Then you confirm.

From your terminal it installs straight away, so pass the scope yourself:

$claude plugin install formatter@your-org --scope project
$claude plugin details formatter     # prints the Always-on token count

The /plugin panel

Three tabs. Press Tab to switch between them.

• Discover: plugins from your marketplaces. Type to search, then Enter for details.
• Installed: Space turns a plugin on or off, f favourites it, and Enter gives Disable, Update now and Uninstall. A Not used recently group lists plugins you could drop.
• Marketplaces: every catalog you added. Update it, switch auto-update on or off, or remove it.

Check what a plugin costs before you install it

An enabled plugin is part of every session, even the ones where you never use it. Each of its skills' and agents' names and descriptions is sent on every turn so Claude knows they exist, and those tokens count toward your usage.

• Before: plugins in the official marketplace show a Context cost with two numbers. Every turn is what the plugin adds to each message you send. When invoked is what its skills and agents add once Claude loads them.
• After: claude plugin details <name> prints an Always-on line, the tokens it adds to every session where it's enabled.
• Running low? The /usage breakdown attributes usage per plugin. Turn off what you don't use with Space in the Installed tab.

Add a marketplace

/plugin marketplace add owner/repo           # a GitHub repo
/plugin marketplace add owner/repo#v1.2.0    # pin a branch or tag
/plugin marketplace add ./my-marketplace     # a local folder needs ./
/plugin market add owner/repo                # shorter form

• A bare name/name is read as a GitHub repo, so start a local path with ./ or ../.
• Any git URL or a hosted marketplace.json works too.
• One step (v2.1.275+): /plugin install deploy-helper --marketplace your-org/plugins offers to add the marketplace, then installs. From the shell it needs v2.1.292+.

Scopes: who gets the plugin

• User: ~/.claude/settings.json. You, in every project. The default from the shell.
• Project: .claude/settings.json, committed for the whole team.
• Local: .claude/settings.local.json. You, in this repo only.
• When a plugin is set at several scopes, local beats project, and project beats user.

A plugin runs code as you

A plugin you install can run any code on your machine with your user privileges. Your permission rules and the sandbox cover the tool calls Claude makes, like calling the plugin's MCP tools or the programs in its bin/ folder. They don't cover the code the plugin runs by itself: its hooks, monitors, MCP servers and LSP servers run outside the sandbox.

The docs give the same warning for every marketplace: "Make sure you trust a plugin before installing, updating, or using it. Anthropic does not control what MCP servers, files, or other software are included in plugins and cannot verify that they will work as intended or that they won't change."

One thing you can rely on: names like claude-plugins-official or claude-community are only accepted from github.com/anthropics/ repos. A copycat stops loading with "Marketplace is registered from an untrusted source".

Updates

• Auto-update is on by default for claude-plugins-official and the other official marketplace names, except knowledge-work-plugins and first-party-plugins.
• It's off for everything else: the community marketplace, third-party marketplaces and local ones. Turn it on per marketplace in the Marketplaces tab.
• The flip side of auto-update: the files you reviewed can change on disk.
• There's no update-all. Update one plugin with Update now, or from the shell:

$claude plugin update commit-commands@claude-plugins-official
$claude plugin marketplace update    # no name: refreshes catalogs only, NOT your plugins

Marketplaces tab, Update marketplace, updates every plugin you got from that catalog. A running session keeps the version it loaded: when you see "Plugin updated: <name> · Run /reload-plugins to apply", run /reload-plugins.

Turn off, uninstall, remove

$claude plugin disable formatter@your-org            # off, still installed
$claude plugin prune                                 # clears dependencies it auto-installed
$claude plugin uninstall formatter --scope project   # gone

• Prefer disable to uninstall when you might want it back. In the panel, that's Space on the Installed tab.
• Uninstalling a plugin the project turned on asks you: y turns it off just for you, u removes it for everyone.
• Removing a marketplace uninstalls every plugin you installed from it. The tab lists them before you confirm.
• Closing the /plugin panel runs /reload-plugins for you, unless reloading would clear the prompt cache. Then it warns you, and /reload-plugins --force applies anyway.

Gotchas

• Cloud sessions (claude.ai/code) don't load the plugins in your local settings.
• In claude -p, /plugin doesn't work, though installed plugins still load. Use claude plugin ... commands there.
• /plugin install inside a session only opens the details page. Nothing is installed until you confirm a scope.
• Context cost only shows for plugins in Anthropic's official marketplace. For anything else, check Always-on with claude plugin details after installing.

Monkey believe in you. Now go build.

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