diff --git a/_specifications/lsp/3.18/language/codeAction.md b/_specifications/lsp/3.18/language/codeAction.md
index 845a7dc8e..6d4a803d9 100644
--- a/_specifications/lsp/3.18/language/codeAction.md
+++ b/_specifications/lsp/3.18/language/codeAction.md
@@ -364,6 +364,8 @@ export interface CodeActionContext {
 	 * 
 	 * Note that the client should check the `textDocument.diagnostic.markupMessageSupport`
 	 * server capability before sending diagnostics with markup messages to a server.
+	 * Diagnostics with markup messages should be excluded for servers that don't support
+	 * them.
 	 */
 	diagnostics: Diagnostic[];