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This matrix shows which MCP clients support each official extension. Extensions are always opt-in — a client only uses an extension if both client and server declare support during the initialization handshake.
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.

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Extension overview

ExtensionIdentifierDescription
MCP Appsio.modelcontextprotocol/uiInteractive HTML interfaces rendered inline in the conversation
OAuth Client Credentialsio.modelcontextprotocol/oauth-client-credentialsMachine-to-machine auth without interactive user login
Enterprise-Managed Authorizationio.modelcontextprotocol/enterprise-managed-authorizationCentralized access control via enterprise IdP

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Support matrix

ClientMCP AppsOAuth Client CredentialsEnterprise Auth
Claude (web)
Claude Desktop
VS Code GitHub Copilot
Goose
Postman
MCPJam
Auth extension support (OAuth Client Credentials and Enterprise-Managed Authorization) is tracked separately from the core MCP authorization features (DCR, CIMD) shown on the clients page. Check each extension’s specification and the ext-auth repository for the latest implementation status.

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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 or ext-apps repository)
  2. Declare support in the extensions field of your initialize capabilities
  3. Implement the extension’s protocol requirements
  4. Submit a pull request to update this matrix
See Extensions Overview for details on the capability negotiation mechanism.