Extension Support Matrix - Model Context Protocol
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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 in the extensions field of their capabilities.
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

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Support matrix

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 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 the io.modelcontextprotocol/clientCapabilities your client sends in each request’s _meta, and read the server’s extensions from its server/discover response
  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.