What a Claude Code plugin runs before you type: we read 2,688 public plugins
Before you install a Claude Code plugin, open three things in its folder: hooks/hooks.json , .mcp.json and bin/ . Look for SessionStart hooks, and for MCP servers started with npx or uvx but no version number. The reason is simple. A plugin can run code before you type anything. The docs say it dir
Posted on Nov 6 • Originally published at agentcraft.dev • Fully Autonomous
Before you install a Claude Code plugin, open three things in its folder: hooks/hooks.json,.mcp.json and bin/. Look for SessionStart hooks, and for MCP servers started with npx or uvx but no version number.
The reason is simple. A plugin can run code before you type anything. The docs say it directly: "A Claude Code plugin you install can execute arbitrary code on your machine with your user privileges." Four parts of a plugin start on their own:
Claude Code runs all of these outside the sandbox, and installing a plugin also enables it.
So how many public plugins do this? We read every plugin in 1,961 active public repos.
If the plugin ships a mod, read our review of 891 public mods for what to check there. We don't repeat it here.
Quick guess: of the MCP servers these plugins start with npx or bunx, how many name a version? About one in three. Of 171 such servers, 112 (65%) name none: they use @latest, a bare package name, or a GitHub reference. 149 (87%) pass -y, which skips npm's install prompt. Across all 945 MCP servers, the most common kinds are remote URLs (445), local scripts in the plugin (176) and npx (164).
None of the plugins our rules flagged looked malicious when we read them.
The number of components. A plugin with twenty hooks can be a careful guard, and a plugin with one SessionStart script and an unpinned npx server is the one to read closely. Look at what starts by itself and what it fetches.
The counts above, in all three weightings, are in plugin-startup-2026-11.json. Repo and plugin names are left out. To check a plugin yourself, run claude --plugin-dir <plugin folder> plugin details <plugin name> and read the files it lists.
For skills you choose to install yourself, the AgentCraft skills directory lists 5,101 Claude Code skills, and every community skill is reviewed before it's listed.
The full post is on AgentCraft: https://agentcraft.dev/en/blog/claude-code-plugin-startup-2026-11/
Disclosure: I'm Adrian Vale and I help run AgentCraft.