diff --git a/hermes_cli/colors.py b/hermes_cli/colors.py
index d30f99c62..8c85b4c0b 100644
--- a/hermes_cli/colors.py
+++ b/hermes_cli/colors.py
@@ -1,8 +1,24 @@
 """Shared ANSI color utilities for Hermes CLI modules."""
 
+import os
 import sys
 
 
+def should_use_color() -> bool:
+    """Return True when colored output is appropriate.
+
+    Respects the NO_COLOR environment variable (https://no-color.org/)
+    and TERM=dumb, in addition to the existing TTY check.
+    """
+    if os.environ.get("NO_COLOR") is not None:
+        return False
+    if os.environ.get("TERM") == "dumb":
+        return False
+    if not sys.stdout.isatty():
+        return False
+    return True
+
+
 class Colors:
     RESET = "\033[0m"
     BOLD = "\033[1m"
@@ -16,7 +32,7 @@ class Colors:
 
 
 def color(text: str, *codes) -> str:
-    """Apply color codes to text (only when output is a TTY)."""
-    if not sys.stdout.isatty():
+    """Apply color codes to text (only when color output is appropriate)."""
+    if not should_use_color():
         return text
     return "".join(codes) + text + Colors.RESET