At its 29 September 2026 DevDay, OpenAI announced support for MCP Events in ChatGPT plugins. A user can tell ChatGPT to watch a connected app for a change, then specify what to do when it arrives. That does not make every existing plugin an event source.
OpenAI’s developer guide describes an event subscription, not a continuously open conversation with the app. ChatGPT subscribes through the plugin’s MCP server; the server sends matching updates to a callback URL, and ChatGPT receives them in the subscribed chat.
What the server must implement
The integration requires MCP 2.0, protocol version 2026-07-28, plus persistent subscription storage and outbound HTTPS access. A server advertises event support, lists events and filters, and handles subscribe and unsubscribe methods on its authenticated MCP endpoint. Developers must keep subscription state across restarts.
For a subscription, ChatGPT provides a callback URL and signing secret. The server must check the user’s access and requested filters, verify the callback with a signed challenge, then sign matching webhook deliveries. An HTTP 2xx acknowledges receipt; ChatGPT processes the event asynchronously. That acknowledgement does not establish that requested follow-up work completed.
Where the limits matter
ChatGPT’s integration supports webhooks, not polling or streaming. It also omits the draft specification’s gap and terminated control notifications. Replay requires the server to support cursors; if an event type has no replay, updates missed during an interruption cannot be recovered through this protocol. OpenAI’s guide warns that events may arrive out of order and recommends idempotent write tools so retries do not duplicate changes.
For builders, this is server operations work as well as integration work: test expired subscriptions, revoked access, duplicate deliveries and feedback loops before relying on an event to start a workflow.
Separately, OpenAI’s plugin extensions guide describes sidebar apps, conversation panels and file viewers. Composer mentions are desktop-only, while web extensions for Free and Go are listed as coming soon. Those surfaces change where a plugin appears; MCP Events changes how subscribed updates reach a chat.
