Agent MCP server configuration. Name and URL are required. Name must be unique for the
agent (max 50 characters) and URL must be a valid HTTP/HTTPS URL. Optional fields include
transport_type (defaults to 'http'), auto_approve array, and timeout (defaults to 30).
Creates an agent-specific MCP server configuration. Agent must use an OpenAI model to
support MCP. Requires a valid paid account (payment_required middleware).