Function build_mcp_registration 

pub fn build_mcp_registration(
    client: Arc<McpClient>,
    provider: &str,
    tool: &McpToolInfo,
    server_hint: Option<String>,
) -> ToolRegistration

Build a ToolRegistration for a remote MCP tool.

Naming strategy:

• Primary: mcp::<provider>::<tool>
• Alias: mcp__<provider>__<tool> (sanitized and length-capped for model compatibility).