diff --git a/AGENTS.md b/AGENTS.md
index 2a4b74a3f4c..ccb386f7ff5 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -56,7 +56,7 @@ Other top-level areas:
 
 Follow these project docs instead of duplicating their contents:
 
-- `docs/CodeStyle.md` for C/C++ formatting and naming.
+- `docs/CodeStyle.md` for C/C++ formatting, naming, and comment style.
 - `docs/LoggingStyle.md` for log levels and message style.
 - `docs/OptimizationStyle.md` for performance-sensitive changes.
 - `REVIEW.md` for UCX pull-request review checks and comment style.
diff --git a/docs/CodeStyle.md b/docs/CodeStyle.md
index a7aa9ad1f21..e96bfa8edda 100644
--- a/docs/CodeStyle.md
+++ b/docs/CodeStyle.md
@@ -18,6 +18,16 @@
   * Use `ucs_assert*` for internal invariants, not user-input validation.
 
 
+## Comments
+  * Usually one line; use more only for a non-obvious or complex point, or
+    per the `## Doxygen` section below.
+  * Focus on "why" rather than "what"; no PR/issue references, no dev-process
+    narration.
+  * Document once, in the most relevant area.
+  * Explain locking, ownership, tradeoffs, or step-by-step processing when
+    non-obvious.
+
+
 ## Naming convention:
   * Lower case, underscores
   * Names must begin with ucp_/uct_/ucs_/ucm_