Plugins and skills

Plugins and skills teach the agent the tools and the ways of working you use.

• A plugin adds tools, commands and skills to the agent, often by connecting a service or a program through an MCP server. You install it once and every session can use it.
• A skill is written know-how: a SKILL.md file that tells the agent how to do one kind of task, such as your deploy steps or a review checklist. The agent loads it when a task matches, or when you call it by name.

AgenC Core installs, runs and loads both. The Plugins page in the app is where you browse, install and manage them.

Open the Plugins page

Click Plugins in the sidebar. The page has two tabs, Plugins and Skills, a search box, a refresh button, a gear that opens the manager ("Manage plugins"), and an Add menu with Add marketplace and Add MCP server. Settings > Advanced > MCP & plugins > Manage opens the same manager.

The Plugins page is not available from a phone or another browser.

Browse and install plugins

The browse view shows what you have installed at the top, then the catalogue, filtered by Public or Personal and grouped into Featured, Productivity and Creativity. The catalogue is what your configured marketplaces offer, so it changes as they do.

Each card shows the plugin's name, description and, once installed, its trust and update labels. Click Install to install it. An installed card's menu offers Try now, Manage and Uninstall. Try now starts a new chat with the plugin named in the composer.

Click a card for the plugin's page: its description, example prompts, the skills and commands it adds (each command with its arguments), its settings, and information such as developer, version, source, commit and the digest of what was installed. Copy link copies its website.

After you install, remove, enable, disable or update a plugin, the app asks Core to reload its configuration. Nothing needs a restart.

Manage plugins

The manager has five tabs:

• Plugins: installed plugins with an on and off switch, Update when an update is available, and Uninstall.
• Apps: apps that plugins ship, each with Manage plugin.
• MCPs: MCP servers, yours and those from plugins; see below.
• Skills: every skill Core has loaded; see below.
• Marketplace: the sources AgenC checks for plugins and updates.

Trust and update labels

An installed plugin carries two labels. The trust label says what Core could verify about where it came from:

• "Verified signature", or "Verified, signed by" and the publisher's key: Core verified the plugin's signature.
• "Unsigned local plugin": installed from a local folder, without a signature.
• "Verification failed": Core's check failed.

The update label says what Core knows about newer versions:

• "Update available": a verified update exists, including a changed signed package at the same version.
• "Up to date".
• "Update check unavailable": the check could not be verified.

"Needs setup" means the plugin has required settings you have not filled in yet. Click it to open the plugin's settings.

Plugin settings and secrets

A plugin can ask for settings, such as a folder, an account name or an API key. They appear in the Settings section of its page, once it is installed. Fields can be text, numbers, on and off choices, folders, files, lists and secrets. Required fields are marked with an asterisk.

• Click Save. The app says "Saved. Reconnect the plugin server to apply changes." Settings take effect when the plugin's server starts again. A session that is already running keeps the settings it started with; a new session uses the new ones.
• Secrets are stored by Core in secure storage and never shown back. A saved secret reads "Set. Enter a new value to replace it." Leave it empty to keep it.
• Reset all settings clears every setting and, after a warning that names them, every saved secret.

Commands and skills in the chat

In the composer, type / at the start of a line to see plugin commands and skills, or @ to see plugins and skills. After you pick a command, a grey hint shows the arguments it takes. The + menu also lists your enabled plugins. See Writing messages.

MCP servers

MCP servers are programs that give the agent tools. Plugins bring their own servers; you can also add any server yourself.

The MCPs tab of the manager lists Servers you added and servers From plugins. Each has a switch, and a gear to configure it when you may edit it. A server that needs a sign-in shows Connect, which opens the sign-in in your browser; it then shows "Connected" with Disconnect. Only one sign-in runs at a time. Core keeps the credentials in secure storage.

Core starts a plugin's server when a tool needs it and stops it when it is idle, so many installed plugins do not keep many programs running.

Add your own MCP server

Choose Add > Add MCP server, or Add server on the MCPs tab. The form, "Connect to a custom MCP", asks for:

• Name;
• Type: STDIO for a program on this computer, or Streamable HTTP or SSE for a remote server;
• Command to launch (for example npx) and its Arguments, or the Server URL;
• Authentication: None or OAuth, for remote servers, with an optional client ID and scopes;
• Environment variables, Environment variable passthrough and a Working directory.

Click Save. Changes apply to new sessions. Saved secret values show as "Saved value" and are kept unless you change or delete them.

Marketplaces

A marketplace is a source of plugins: a GitHub repository, a Git URL or a local folder. When you have none, Core adds AgenC's own marketplace, agenc-plugins, and reads it again about once an hour. The Marketplace tab lists yours, with how many plugins each offers. Add marketplace asks for the source, an optional Git ref (such as main) and optional sparse paths inside it. Upgrade or Refresh reads a marketplace again, and the remove button drops it.

The app has no way to publish a plugin. To use your own, put it in a local folder or a Git repository and add that as a marketplace. Plugins from a local source, or from a marketplace named personal, appear under Personal.

Skills

The Skills tab lists every skill Core serves to your sessions:

• skills that come with Core, labeled "Built-in";
• your personal and project skills;
• skills that plugins provide, labeled "Provided by" and the plugin.

Filter them by Personal, System (built-in and managed skills) or Recommended (mostly plugin skills). Click a skill to read its instructions. For skills stored as files, the menu offers Open (opens SKILL.md in your default app), Reveal in Finder and Copy Markdown. Try now starts a chat with the skill's command. Uninstall moves a personal skill's folder to the trash, or uninstalls the plugin that provides it.

If Core skipped or limited some skills, the manager's Skills tab shows a list of skill warnings with the reason for each.

Add a skill

The app has no button to write a skill. Create a folder with a SKILL.md file in it, in one of the places Core reads, then click refresh on the Plugins page. Personal skills go in the skills folder of the app's Core data folder (see Data and privacy); project skills go in .agenc/skills inside the project. The file format and every place Core looks are in the AgenC Core guide.

Skills have no on and off switch of their own. A plugin's skills follow the plugin's switch.