Is your feature request related to a problem? Please describe.
mcp 2.0 supports SEP-2133 extension advertisement: create_initialization_options(extensions=...) publishes supported extensions under ServerCapabilities.extensions, keyed by identifier (e.g. io.modelcontextprotocol/ui).
ag2.mcp_ui has a concrete use for this. Today a client cannot know that a served agent offers UI resources until it calls a tool and inspects what came back. Declaring io.modelcontextprotocol/ui at initialize time makes the capability discoverable up front — which is, as it happens, what mcp-ui#74 ("Is there a way server to detect the client supports mcp-ui?") is asking for from the other direction.
Describe the solution you'd like
Advertise SEP-2133 extensions from ag2.mcp.MCPServer, and have ag2.mcp_ui declare io.modelcontextprotocol/ui when UI resources are in play.
Worth checking before building: whether the mcp-ui spec has settled on this identifier and on what the per-extension settings payload should contain.
Additional context
Sub-issue of #3183.
Is your feature request related to a problem? Please describe.
mcp2.0 supports SEP-2133 extension advertisement:create_initialization_options(extensions=...)publishes supported extensions underServerCapabilities.extensions, keyed by identifier (e.g.io.modelcontextprotocol/ui).ag2.mcp_uihas a concrete use for this. Today a client cannot know that a served agent offers UI resources until it calls a tool and inspects what came back. Declaringio.modelcontextprotocol/uiat initialize time makes the capability discoverable up front — which is, as it happens, what mcp-ui#74 ("Is there a way server to detect the client supports mcp-ui?") is asking for from the other direction.Describe the solution you'd like
Advertise SEP-2133 extensions from
ag2.mcp.MCPServer, and haveag2.mcp_uideclareio.modelcontextprotocol/uiwhen UI resources are in play.Worth checking before building: whether the mcp-ui spec has settled on this identifier and on what the per-extension settings payload should contain.
Additional context
Sub-issue of #3183.