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

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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.

<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.

Extension overview

Support matrix

<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 for the latest implementation status.

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.

Last updated Oct 08, 2026