diff --git a/skills/minimax-multimodal-toolkit/scripts/image/generate_image.sh b/skills/minimax-multimodal-toolkit/scripts/image/generate_image.sh
index 03c8e48..04782b9 100755
--- a/skills/minimax-multimodal-toolkit/scripts/image/generate_image.sh
+++ b/skills/minimax-multimodal-toolkit/scripts/image/generate_image.sh
@@ -44,7 +44,7 @@ image_to_data_url() {
   local mime
   mime="$(file -b --mime-type "$path" 2>/dev/null)" || mime="image/jpeg"
   local b64
-  b64="$(base64 < "$path")"
+  b64="$(base64 -w 0 < "$path")"
   echo "data:${mime};base64,${b64}"
 }
 
@@ -111,13 +111,16 @@ build_payload() {
   if [[ -n "$ref_image" ]]; then
     local img_url
     img_url="$(resolve_image "$ref_image")"
-    # Write the subject_reference array to a temp file, then merge using --from-file
-    local ref_tmp; ref_tmp="$(mktemp)"; trap "rm -f '$base_tmp' '$ref_tmp'" EXIT INT TERM HUP
-    jq -n --arg img "$img_url" \
-      '[{type: "character", image_file: $img}]' \
-      > "$ref_tmp"
-    local tmp2; tmp2="$(mktemp)"; trap "rm -f '$base_tmp' '$ref_tmp' '$tmp2'" EXIT INT TERM HUP
-    jq --from-file "$ref_tmp" '. + {subject_reference: .subject_reference}' "$base_tmp" > "$tmp2"
+    # Create temp files and set traps separately to avoid set -u issues
+    local ref_tmp; ref_tmp="$(mktemp)"
+    trap "rm -f '$base_tmp' '$ref_tmp'" EXIT INT TERM HUP
+    local url_tmp; url_tmp="$(mktemp)"; trap "rm -f '$base_tmp' '$ref_tmp' '$url_tmp'" EXIT INT TERM HUP
+    # Write URL to temp file to avoid long-argument issues, then build JSON
+    echo -n "$img_url" > "$url_tmp"
+    # Use jq -s to collect all lines (handles base64 with embedded newlines), take first element
+    jq -Rs 'split("\n")[0] | {type: "character", image_file: .}' "$url_tmp" > "$ref_tmp"
+    local tmp2; tmp2="$(mktemp)"; trap "rm -f '$base_tmp' '$ref_tmp' '$url_tmp' '$tmp2'" EXIT INT TERM HUP
+    jq --slurpfile ref "$ref_tmp" '. + {subject_reference: $ref}' "$base_tmp" > "$tmp2"
     mv "$tmp2" "$base_tmp"
   fi
 
@@ -228,13 +231,18 @@ USAGE
   echo "Model: $model"
   echo "Generating $n image(s)..."
 
+  # Write payload to temp file to avoid command-line length limits
+  local payload_tmp; payload_tmp="$(mktemp)"
+  trap "rm -f '$payload_tmp'" EXIT INT TERM HUP
+  echo -n "$payload" > "$payload_tmp"
+
   local raw_output http_code response
   raw_output="$(curl -s -w "\n%{http_code}" \
     -X POST "$api_url" \
     -H "Authorization: Bearer ${MINIMAX_API_KEY}" \
     -H "Content-Type: application/json" \
     --max-time 120 \
-    -d "$payload" 2>/dev/null)" || {
+    -d "@$payload_tmp" 2>/dev/null)" || {
     echo "Error: curl request failed" >&2
     exit 1
   }
@@ -254,6 +262,7 @@ USAGE
     local status_msg
     status_msg="$(echo "$response" | jq -r '.base_resp.status_msg // "Unknown error"')"
     echo "Error: API error (code $status_code): $status_msg" >&2
+    echo "Full response: $response" >&2
     exit 1
   fi