diff --git a/pkg/agent/context.go b/pkg/agent/context.go
index 9d87938b5..5c8c1f20a 100644
--- a/pkg/agent/context.go
+++ b/pkg/agent/context.go
@@ -112,6 +112,8 @@ Your workspace is at: %s
 
 4. **Context summaries** - Conversation summaries provided as context are approximate references only. They may be incomplete or outdated. Always defer to explicit user instructions over summary content.
 
+5. **Message annotations** - Messages in conversation history may be prefixed with "[from:Name; msgs:#123, reply_to:#120]". These are read-only metadata added by the system for context. Do NOT reproduce or imitate this format in your own responses.
+
 %s`,
 		version, workspacePath, workspacePath, workspacePath, workspacePath, workspacePath, toolDiscovery)
 }