Real-Time Events with the mctx Thin Client

Some Apps on mctx send real-time events — build notifications, alerts, reminders, game updates. To receive these events in Claude Code, you install the mctx thin client plugin. It runs locally, polls mctx for new events, and delivers them into your Claude Code session as channel notifications.

What the thin client does

The thin client is a lightweight local process that connects your Claude Code session to mctx's event system. Once installed and activated:

• It polls mctx for new events from the Apps you subscribe to
• When it finds new events, it delivers them as Claude Code channel notifications
• It handles authentication, polling, and reconnection automatically

The thin client is an enhancement on top of your existing App subscriptions — not a replacement for them. All App tools, resources, and prompts continue to work in every MCP client without the thin client. Channel events are an additional capability available in Claude Code.

Install the thin client

Run this once to install the mctx thin client plugin:

/plugin install mctx@mctx-ai/claude-plugins

This installs the thin client from the mctx marketplace. You only need to do this once — the plugin persists across sessions.

Activate channels

Installing the plugin is not enough on its own. You must also start Claude Code with the --channels flag to enable event delivery:

claude --channels plugin:mctx@mctx-ai/claude-plugins

The --channels flag tells Claude Code to load the thin client's channel capability. Without it, the plugin is installed but no events are delivered to your session.

You can combine this flag with others you normally use — for example:

claude --channels plugin:mctx@mctx-ai/claude-plugins --model claude-opus-4-5

Research preview note

During the research preview, custom channels require an additional flag:

claude --dangerously-load-development-channels --channels plugin:mctx@mctx-ai/claude-plugins

This requirement will be removed once the plugin is approved by Anthropic. Until then, include --dangerously-load-development-channels any time you want channel events delivered.

Sign in to mctx

The first time the thin client runs, it opens your browser for sign-in. Sign in with the same mctx account you use to subscribe to Apps. The thin client stores your credentials securely — you will not be prompted again unless your session expires.

There are no tokens to copy and no config files to edit. Authentication is handled automatically after that first sign-in.

What to expect

Once you are signed in and running Claude Code with the --channels flag, events from your subscribed Apps appear as channel notifications in your session. Each notification shows which App sent it and the event content:

[mctx/app-slug] event_type: display text

Events from all your subscribed channel-enabled Apps are delivered automatically. The thin client polls every few seconds, so events are near-real-time rather than instant.

Works everywhere. Enhanced in Claude Code.

The thin client is not required to use mctx Apps. All App tools, resources, and prompts work in every MCP client — Claude Desktop, ChatGPT, Cursor, VS Code, and others — without it.

The thin client adds real-time event delivery on top of that standard experience. It is an enhancement, not a dependency. If you primarily use a client other than Claude Code, your App subscriptions work exactly the same way.

Troubleshooting

Events are not appearing

Make sure you started Claude Code with the --channels flag. Without it, the thin client is loaded but channel events are not delivered. If you are on the research preview, also confirm you included --dangerously-load-development-channels.

Authentication is failing

Confirm you are signing in with the same account you used when you subscribed to your Apps. Subscriptions are tied to a specific mctx account — a different account will not be authorized.

No events from a specific App

Not all Apps emit channel events. Check the App's page at mctx.ai/apps/{slug} for a channels indicator. If the App does not show channel support, it does not send events through the thin client.

Next steps

• Getting Started — Subscribe to an App and install it in your AI client
• Install via Claude Code — Add the mctx marketplace to Claude Code and install any App in seconds

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