diff --git a/README.md b/README.md
index 8e9c1ff..47a4ac4 100644
--- a/README.md
+++ b/README.md
@@ -414,7 +414,8 @@ index/log/provenance regeneration, structural linting, and publishing.
 Every command carries one data record - synopsis, properties, copyable examples,
 each exit cause with what to do about it, prohibitions, and notes on its
 behaviour - kept next to its code. `tools/wikitool <command> -h` prints it,
-`tools/wikitool -h` prints a one-line index of all of them, and
+`tools/wikitool -h` prints a one-line index of all of them, a command that fails with
+exit 1 prints the record's reactions on stderr right under its `ERROR` line, and
 [`tools/CONTRACT.md`](tools/CONTRACT.md) holds a generated copy together with the
 maintenance schedule; `tools/wikitool docs verify` checks that copy and every
 command's flags against the CLI in both directions. [`tools/README.md`](tools/README.md)