diff --git a/scripts/bash/create-new-feature.sh b/scripts/bash/create-new-feature.sh
index c40cfd77f0..54697024d6 100644
--- a/scripts/bash/create-new-feature.sh
+++ b/scripts/bash/create-new-feature.sh
@@ -67,6 +67,13 @@ if [ -z "$FEATURE_DESCRIPTION" ]; then
     exit 1
 fi
 
+# Trim whitespace and validate description is not empty (e.g., user passed only whitespace)
+FEATURE_DESCRIPTION=$(echo "$FEATURE_DESCRIPTION" | xargs)
+if [ -z "$FEATURE_DESCRIPTION" ]; then
+    echo "Error: Feature description cannot be empty or contain only whitespace" >&2
+    exit 1
+fi
+
 # Function to find the repository root by searching for existing project markers
 find_repo_root() {
     local dir="$1"
@@ -272,7 +279,16 @@ if [ ${#BRANCH_NAME} -gt $MAX_BRANCH_LENGTH ]; then
 fi
 
 if [ "$HAS_GIT" = true ]; then
-    git checkout -b "$BRANCH_NAME"
+    if ! git checkout -b "$BRANCH_NAME" 2>/dev/null; then
+        # Check if branch already exists
+        if git branch --list "$BRANCH_NAME" | grep -q .; then
+            >&2 echo "Error: Branch '$BRANCH_NAME' already exists. Please use a different feature name or specify a different number with --number."
+            exit 1
+        else
+            >&2 echo "Error: Failed to create git branch '$BRANCH_NAME'. Please check your git configuration and try again."
+            exit 1
+        fi
+    fi
 else
     >&2 echo "[specify] Warning: Git repository not detected; skipped branch creation for $BRANCH_NAME"
 fi
diff --git a/scripts/powershell/create-new-feature.ps1 b/scripts/powershell/create-new-feature.ps1
index 2f0172e35d..0bc7f7b473 100644
--- a/scripts/powershell/create-new-feature.ps1
+++ b/scripts/powershell/create-new-feature.ps1
@@ -35,6 +35,12 @@ if (-not $FeatureDescription -or $FeatureDescription.Count -eq 0) {
 
 $featureDesc = ($FeatureDescription -join ' ').Trim()
 
+# Validate description is not empty after trimming (e.g., user passed only whitespace)
+if ([string]::IsNullOrWhiteSpace($featureDesc)) {
+    Write-Error "Error: Feature description cannot be empty or contain only whitespace"
+    exit 1
+}
+
 # Resolve repository root. Prefer git information when available, but fall back
 # to searching for repository markers so the workflow still functions in repositories that
 # were initialized with --no-git.
@@ -242,10 +248,26 @@ if ($branchName.Length -gt $maxBranchLength) {
 }
 
 if ($hasGit) {
+    $branchCreated = $false
     try {
-        git checkout -b $branchName | Out-Null
+        git checkout -b $branchName 2>&1 | Out-Null
+        if ($LASTEXITCODE -eq 0) {
+            $branchCreated = $true
+        }
     } catch {
-        Write-Warning "Failed to create git branch: $branchName"
+        # Exception during git command
+    }
+
+    if (-not $branchCreated) {
+        # Check if branch already exists
+        $existingBranch = git branch --list $branchName 2>$null
+        if ($existingBranch) {
+            Write-Error "Error: Branch '$branchName' already exists. Please use a different feature name or specify a different number with -Number."
+            exit 1
+        } else {
+            Write-Error "Error: Failed to create git branch '$branchName'. Please check your git configuration and try again."
+            exit 1
+        }
     }
 } else {
     Write-Warning "[specify] Warning: Git repository not detected; skipped branch creation for $branchName"