diff --git a/Documentation/gitcredentials.txt b/Documentation/gitcredentials.txt
index 1814d2d23c..31cd7fde10 100644
--- a/Documentation/gitcredentials.txt
+++ b/Documentation/gitcredentials.txt
@@ -262,16 +262,26 @@ For a `get` operation, the helper should produce a list of attributes on
 stdout in the same format (see linkgit:git-credential[1] for common
 attributes). A helper is free to produce a subset, or even no values at
 all if it has nothing useful to provide. Any provided attributes will
-overwrite those already known about by Git.  If a helper outputs a
-`quit` attribute with a value of `true` or `1`, no further helpers will
-be consulted, nor will the user be prompted (if no credential has been
-provided, the operation will then fail).
+overwrite those already known about by Git's credential subsystem.
+
+While it is possible to override all attributes, well behaving helpers
+should refrain from doing so for any attribute other than username and
+password.
+
+If a helper outputs a `quit` attribute with a value of `true` or `1`,
+no further helpers will be consulted, nor will the user be prompted
+(if no credential has been provided, the operation will then fail).
+
+Similarly, no more helpers will be consulted once both username and
+password had been provided.
 
 For a `store` or `erase` operation, the helper's output is ignored.
-If it fails to perform the requested operation, it may complain to
-stderr to inform the user. If it does not support the requested
-operation (e.g., a read-only store), it should silently ignore the
-request.
+
+If a helper fails to perform the requested operation or needs to notify
+the user of a potential issue, it may write to stderr.
+
+If it does not support the requested operation (e.g., a read-only store),
+it should silently ignore the request.
 
 If a helper receives any other operation, it should silently ignore the
 request. This leaves room for future operations to be added (older