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Plugin Extensions

OpenAI released MCP Extensions, a set of plugin extensions that let developers hook their plugins into ChatGPT surfaces including the sidebar, composer, and file viewers, with TypeScript and Python SDKs and a formal protocol specification published on GitHub. Plugin extensions on the web are coming soon to ChatGPT Free and Go users, existing plugin functionality is unaffected, and composer mentions are available only in the ChatGPT desktop app. The extensions cover sidebar apps, conversation panels, plugin settings, file viewers and editors, display modes, deep links, Model-App Context, composer mentions, and rich forms.

read4 min views1 publishedSep 29, 2026
Plugin Extensions
Image: Developers (auto-discovered)

OpenAI MCP Extensions enables developers to hook their plugins into key surfaces of the ChatGPT user experience, including the sidebar, composer, and file viewers.

Plugin extensions on the web are coming soon to ChatGPT Free and Go users. Existing plugin functionality is unaffected. Composer mentions are available only in the ChatGPT desktop app.

Try it out #

Get a feel for extensions with Bits & Bolts, our kitchen sink plugin. We’ll keep it up to date as new extensions roll out.

Start building #

Use the GitHub repository for installation, SDK examples, and the full specification.

[TypeScript SDK](https://github.com/openai/mcp-extensions/blob/main/typescript/README.md)        

Add extensions to your MCP server and app UI.

[Python SDK](https://github.com/openai/mcp-extensions/blob/main/python/README.md)        

Add server-side extensions with the MCP Python SDK.

[Protocol specification](https://github.com/openai/mcp-extensions/blob/main/docs/spec.md)        

Defines the formal, language-agnostic API that extends the MCP and MCP Apps specifications.

Once your server is ready, connect and test your plugin, then package it for distribution.

Extension reference #

Extensions give users new ways to interact with your plugin across ChatGPT. Declaring support for an extension takes just a few lines of SDK code.

Extension What users can do
Sidebar apps Give users a place to open your app from the sidebar and work in it fullscreen.
Conversation panels Let users open your app beside a conversation, keeping their work and chat together.
Plugin settings Let users configure your plugin’s product-specific settings from within ChatGPT.
File viewers and editors Open supported files in your own interface, with reading, live updates, and saving changes handled together.
Display modes Choose where and how your app appears in ChatGPT conversations.
Deep links Take users directly to a specific page or item within your sidebar app.
Model-App Context Keep ChatGPT and your MCP App in sync with bidirectional context sharing.
Composer mentions Let users find and select content from your plugin in the ChatGPT desktop composer.
Rich forms Ask users for structured input or let them choose from images, then return their response to your tool.

Sidebar apps

Add an entry to the global sidebar that launches your MCP App fullscreen.

Pass this metadata as _meta when registering your MCP App tool. Replace ui://parts/library with your registered UI resource URI:

import type { OpenAIUiToolMetadata } from "@openai/mcp-extensions/server";

const toolMetadata = {
  ui: { resourceUri: "ui://parts/library" },
  "openai/ui": {
    entrypoints: [{ type: "global" }],
  } satisfies OpenAIUiToolMetadata,
};

Use { type: "thread" } to add an entrypoint in a conversation’s side panel. See the entrypoint guide for full registration examples.

File viewers and editors

Open your MCP App in the thread side panel when a user opens a file with a supported extension.

Use a file entrypoint in your tool’s _meta, with the extensions your viewer supports:

import type { OpenAIUiToolMetadata } from "@openai/mcp-extensions/server";

const toolMetadata = {
  ui: { resourceUri: "ui://parts/viewer" },
  "openai/ui": {
    entrypoints: [{ type: "file", extensions: ["stl"] }],
  } satisfies OpenAIUiToolMetadata,
};

Replace ui://parts/viewer with your registered UI resource. The app receives a resource URI for the opened file. Follow the file handler guide to receive that input and read the resource with the app SDK.

Rich forms

Extend standard MCP forms with richer components native to ChatGPT.

import type {
  OpenAIForm,
  OpenAIFormOption,
} from "@openai/mcp-extensions/server";

function partSelectionSchema(parts: OpenAIFormOption[]): OpenAIForm {
  return {
    type: "object",
    properties: {
      part: {
        type: "string",
        title: "Part",
        oneOf: parts,
      },
    },
    required: ["part"],
  };
}

Pass this schema as requestedSchema in your form request. Each option uses const and title, with an optional x-openai-thumbnail icon. OpenAI-registered MCP servers require multi-round-trip requests (MRTR). The SDK’s extended forms guide shows the legacy elicitInput helper for direct MCP connections.

Extensions in the wild #

See how plugins you already know are building with extensions.

Canva

Sidebar Tabs enable Canva users to create designs and preview them as a native sidebar feature of ChatGPT.

View plugin

Figma

Composer Mentions enable Figma users to search for and mention files directly in the ChatGPT desktop app.

View plugin

Adobe

File Extension Handlers enable Adobe users to edit files with Acrobat and Photoshop directly in ChatGPT.

View plugin

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