> ## Documentation Index
> Fetch the complete documentation index at: https://modelcontextprotocol.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Extension Support Matrix

> Which MCP clients implement which official extensions

export const CHECK = () => <span className="flex justify-center">
    <Icon icon="check" iconType="solid" size={18} className="text-green-500" />
  </span>;

This matrix shows which MCP clients support each [official extension](/extensions/overview). Extensions are always opt-in: a client only uses an extension if both client and server declare support in the `extensions` field of their [capabilities](/extensions/overview#negotiation).

<Note>
  This list is maintained by the community. If you notice any inaccuracies or would like to add or update information, please [submit a pull request](https://github.com/modelcontextprotocol/modelcontextprotocol/pulls).
</Note>

## Extension overview

| Extension                                                                             | Identifier                                                 | Description                                                      |
| ------------------------------------------------------------------------------------- | ---------------------------------------------------------- | ---------------------------------------------------------------- |
| [MCP Apps](/extensions/apps/overview)                                                 | `io.modelcontextprotocol/ui`                               | Interactive HTML interfaces rendered inline in the conversation  |
| [OAuth Client Credentials](/extensions/auth/oauth-client-credentials)                 | `io.modelcontextprotocol/oauth-client-credentials`         | Machine-to-machine auth without interactive user login           |
| [Enterprise-Managed Authorization](/extensions/auth/enterprise-managed-authorization) | `io.modelcontextprotocol/enterprise-managed-authorization` | Centralized access control via enterprise IdP                    |
| [Skills over MCP](/extensions/skills/overview)                                        | `io.modelcontextprotocol/skills`                           | Discover skills and read their instructions and supporting files |

## Support matrix

| Client                                                                   | [MCP Apps](/extensions/apps/overview) | [OAuth Client Credentials](/extensions/auth/oauth-client-credentials) | [Enterprise Auth](/extensions/auth/enterprise-managed-authorization) |                                           [Skills](/extensions/skills/overview)                                          |
| ------------------------------------------------------------------------ | :-----------------------------------: | :-------------------------------------------------------------------: | :------------------------------------------------------------------: | :----------------------------------------------------------------------------------------------------------------------: |
| [Claude (web)](https://claude.ai)                                        |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [Claude Desktop](https://claude.ai/download)                             |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [VS Code GitHub Copilot](https://code.visualstudio.com/)                 |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [Microsoft 365 Copilot](https://www.microsoft.com/microsoft-365-copilot) |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [Goose](https://block.github.io/goose/)                                  |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [Postman](https://postman.com)                                           |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [MCPJam](https://www.mcpjam.com/)                                        |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [ChatGPT](https://chatgpt.com/)                                          |               <CHECK />               |                                                                       |                                                                      |            [Partial](https://developers.openai.com/plugins/build/mcp-server#import-skills-from-the-mcp-server)           |
| [Cursor](https://cursor.com/)                                            |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [Archestra.AI](https://www.archestra.ai/)                                |               <CHECK />               |                                                                       |                               <CHECK />                              |                                                                                                                          |
| [PostHog Code](https://posthog.com/code/)                                |               <CHECK />               |                                                                       |                                                                      |                                                                                                                          |
| [fast-agent](https://github.com/evalstate/fast-agent)                    |                                       |                                                                       |                                                                      |               [Partial](https://github.com/evalstate/fast-agent/blob/main/docs/docs/mcp/skills-over-mcp.md)              |
| [MCP Inspector](https://github.com/modelcontextprotocol/inspector)       |                                       |                                                                       |                                                                      | [Partial](https://github.com/modelcontextprotocol/inspector/blob/main/clients/cli/README.md#skill-verification---verify) |

<Note>
  Auth extension support (OAuth Client Credentials and Enterprise-Managed Authorization) is tracked separately from the core MCP authorization features (DCR, CIMD). Check each extension's specification and the [ext-auth repository](https://github.com/modelcontextprotocol/ext-auth) for the latest implementation status.
</Note>

## Adding extension support to your client

If you're building an MCP client and want to implement extension support:

1. Review the extension specification (e.g., in the [ext-auth](https://github.com/modelcontextprotocol/ext-auth) or [ext-apps](https://github.com/modelcontextprotocol/ext-apps) repository)
2. Declare support in the `extensions` field of the `io.modelcontextprotocol/clientCapabilities` your client sends in each request's `_meta`, and read the server's `extensions` from its [`server/discover`](/specification/draft/server/discover) response
3. Implement the extension's protocol requirements
4. Submit a pull request to update this matrix

See [Extensions Overview](/extensions/overview#negotiation) for details on the capability negotiation mechanism.