try

helpers/CheckJsonSchema.ps1

@@ -7,6 +7,7 @@ Install-Module -Name GripDevJsonSchemaValidator -Force  -Scope CurrentUser
 $toolsetFiles = Get-ChildItem -Recurse -Filter "toolset-*.json" | Where-Object { $_.Name -notlike "*schema.json" }
 $schemaFilePath = "./schemas/toolset-schema.json"
 
+$toolsetHasErrors = $false
 foreach ($file in $toolsetFiles) {
     Write-Host "🔍 Validating $($file.FullName)" -ForegroundColor Cyan
 
@@ -15,15 +16,21 @@ foreach ($file in $toolsetFiles) {
     if ($validationResult.Valid) {
         Write-Host "✅ JSON is valid." -ForegroundColor Green
     } else {
+        $toolsetHasErrors = $true
         Write-Host "`n❌ JSON validation failed!" -ForegroundColor Red
         Write-Host "   Found the following errors:`n" -ForegroundColor Yellow
         $validationResult.Errors | ForEach-Object {
             Write-Host $_.UserMessage
             if ($env:GITHUB_ACTIONS -eq 'true') {
-                Write-Host "::error file=$($file.Name),line=$($_.LineNumber)::$($_.UserMessage)"
+                Write-Host "Adding annotation"
+                Write-Host "::error file=$($file.Name),line=$($_.LineNumber)::$($_.UserMessage.Replace("`n", '%0A'))"
             }
         }
     }
 }
 
-Write-Host "Schema validation completed successfully"
+if ($toolsetHasErrors) {
+    Write-Error "One or more toolset JSON files failed schema validation. See the error output above for more details."
+} else {
+    Write-Host "Schema validation completed successfully"
+}