How to install a plugin, skill or extension

Plugin, skill, extension, connector and MCP server all mean roughly the same thing: a package that gives an AI app a new ability. Each product uses its own word and its own menu, and the menus move around between releases. The steps below show where to look. When a name differs on your screen, search the settings for the word extension or connector.

Before you install anything

Treat an add-on like a program you run on your computer, because that is what it is. Install it only from the vendor store or from a repository you can read. Check who published it, read what it asks permission for, and start with read-only access. A skill is a folder of instructions and a connector is a live link to a service, so both can read whatever you let them reach. The prompt-injection page explains why that matters.

In a chat app (Claude, ChatGPT, Gemini)

Open settings and look for a section called Connectors, Integrations, Apps or Capabilities. That is where you switch on a service such as Google Drive or Slack. You sign in to the service, approve the scope it asks for, and the connector appears in new chats.

Claude. Skills are uploaded or enabled in the Capabilities or Skills part of settings. You normally upload a skill as a .zip file whose folder contains a SKILL.md file. Connectors sit in the same settings area.

ChatGPT. Go to the GPT store or the Apps section, open the one you want and press Add or Start chat. Your own Custom GPT is created from the Explore GPTs page.

Gemini. Extensions and connected apps live under settings, in the connected apps part.

After you install, open a new chat and ask the assistant to use the add-on by name. If it cannot see it, switch the add-on on for that chat, since it is often off by default.

In a program on your computer

Claude Code (terminal). Run claude inside your project. Plugins install from a marketplace with the /plugin command: add a marketplace, then install a plugin from it. A skill is a folder with a SKILL.md file. Put it in ~/.claude/skills/ for every project or in .claude/skills/ inside one project, and restart the session. An MCP server is added with claude mcp add. Check what is loaded with /mcp and /plugin.

Cursor. Open Settings and find the MCP section, or create .cursor/mcp.json in your project and list the server there. Project rules go in .cursor/rules/. Restart Cursor after you edit the file.

VS Code. Open the Extensions panel with Ctrl+Shift+X (Cmd+Shift+X on a Mac), search for the extension, such as Continue or GitHub Copilot, and press Install. Sign in when it asks.

Google Antigravity. It is a VS Code fork with an agent built in, so extensions install the same way: open the Extensions panel with Ctrl+Shift+X, search and press Install. Extensions come from the Open VSX registry, so a few that exist only on the Microsoft marketplace may be missing. MCP servers are managed from the agent panel, in its MCP or Manage MCP Servers option, where you can also edit the raw config file. The names in this app are new and change fast, so look for the words extension, MCP and rules in its settings.

Ollama and LM Studio. These two install models and have no plugins. In Ollama you run ollama pull name. In LM Studio you search and download inside the app. See running-a-model-on-your-own-machine.

Where the settings file lives

Most tools keep the setup in a plain file: a mcp.json, a settings.json, a CLAUDE.md. That is good news. You can read it, copy it to another computer and keep it in git. Put secrets such as API keys in environment variables and keep them out of the file you share.

If it does not work

Restart the app first, since most add-ons load only at startup. Then check the add-on is switched on for this project or chat. Then read the log or the error line: a missing Node.js or Python on your PATH is the usual cause for an MCP server that will not start. Last, remove the add-on and install it again before you search the web for an answer.

Remove what you do not use

Every active add-on adds instructions to the context window and widens what the model can reach. Uninstall anything you have not used in a month. moving-your-rules-into-a-config-file shows where your standing rules belong instead.