MCP Extensions Explained
Extensions add optional functionality without bloating or destabilizing the core protocol. A client or server that does not recognize an extension can continue using baseline MCP.
Identifiers
Official extensions use the io.modelcontextprotocol vendor prefix. Third parties should use a reversed domain they control to avoid naming collisions.
Negotiation
Extensions are opt-in. Both sides need compatible support before extension behavior should be used.
Current examples
- MCP Apps.
- Tasks.
- OAuth Client Credentials.
- Enterprise-Managed Authorization.