Declare a transport on the service
Service entry has no "transport" field and no legacy nested transport.
Why it matters
Without a transport, agents do not know whether to speak REST, MCP, or A2A to your endpoint.
Show fix
Allowed transport values per spec: rest, mcp, a2a, embedded.
{
"version": "2026-08-25",
"transport": "mcp",
"endpoint": "https://yourstore.com/api/ucp/mcp"
}
