In a chat, @ names an agent or a plugin and / picks a skill; a plugin your agent needs but has off asks you to turn it on; Add custom adds a plugin bundle or an MCP server of your own.
- Type @ in the message box. After the people in the chat, the list shows your agents and the plugins you have added; keep typing to filter, then press Return or Tab to insert one, such as
@Slack. - Type / at the start of the message or after a space to list your skills, and insert one, such as
/brand-voice. - When an agent wants a plugin that is off for it or for this chat, a card asks the chat's owner Turn on …? Choose Allow for this task to turn it on for this chat only, Always on to turn it on for the agent too, or Not now. A tool the agent asked for runs as soon as you allow it; for a connected app the agent tries again on its next turn.
- To add your own, open Plugins and click Add custom at the top right. Paste a GitHub repository (a plugin bundle in Claude Code's format, such as
owner/repo) or an MCP server's https address; for a server, add its token if it needs one, or choose the agent that uses it.
Where: Web and Mac — the message box of a chat with an agent, the card in the conversation, and Plugins › Add custom.
For agents: sky plugins off|on <id> --session <chat> switches a plugin for one chat (on, for a chat whose agent has it off, turns it on for that chat alone); sky plugins install <github address> or sky plugins add --mcp-url <address> [--token] [--agent] adds your own. MCP tools: set_plugin_off, install_plugin and add_plugin. API: PUT /v1/plugins/{id}/off and POST /v1/plugins.
Good to know: an MCP server's token is kept in the workspace's vault and sent to the server on every call; without a token, choose the agent it belongs to. Switching a plugin on for a chat never adds a plugin the workspace has not added. Related: What are skills?, Use AgentSky as an MCP server, See who is here, assign a chat and mention a teammate.