Extension declaration for MCP Apps #777
Description
The MCP Apps extension denotes that a client supporting MCP Apps should declare its capability as follows.
{
"method": "initialize",
"params": {
"protocolVersion": "2024-11-05",
"capabilities": {
"extensions": {
"io.modelcontextprotocol/ui": {
"mimeTypes": ["text/html;profile=mcp-app"]
}
}
},
"clientInfo": {
"name": "claude-desktop",
"version": "1.0.0"
}
}
}However, ClientCapabilities does not have a field for extensions, so we cannot implement a client that supports MCP Apps extension.
Similarly, MCP servers built with this SDK cannot verify client capabilities in extensions.