diff --git a/c/mapping/mapper_tee.c b/c/mapping/mapper_tee.c
index 82b9ff7fc..f91cc6104 100644
--- a/c/mapping/mapper_tee.c
+++ b/c/mapping/mapper_tee.c
@@ -62,8 +62,14 @@ static mapper_t* mapper_tee_parse_cli(int* pargi, int argc, char** argv) {
 }
 
 static void mapper_tee_usage(FILE* o, char* argv0, char* verb) {
-	fprintf(o, "Usage: %s %s [options]\n", argv0, verb);
-	fprintf(o, "xxx write this up please.\n");
+	fprintf(o, "Usage: %s %s [options] {filename}\n", argv0, verb);
+	fprintf(o, "Passes through input records (like %s cat) but also writes to specified output\n",
+		MLR_GLOBALS.bargv0);
+	fprintf(o, "file, using output-format flags from the command line (e.g. --ocsv). See also\n");
+	fprintf(o, "the \"tee\" keyword within %s put, which allows data-dependent filenames.\n",
+		MLR_GLOBALS.bargv0);
+	fprintf(o, "Options:\n");
+	fprintf(o, "--no-fflush: don't call fflush() after every record.\n");
 }
 
 // ----------------------------------------------------------------
diff --git a/c/todo.txt b/c/todo.txt
index e21f33575..0be1d7800 100644
--- a/c/todo.txt
+++ b/c/todo.txt
@@ -21,9 +21,8 @@ TOP OF LIST:
 
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 COMMON:
-! AST: FILE_WRITE --> stdout/stderr x all
-* put/tee --oxxx flags
 * put/tee --no-flush flags
+* put/tee --oxxx flags
 * mlr -k needs >/>> examples incl. stdout/stderr/file. also some subset at mlr put -h.
 * lrec_reader/writer take sub-bagged cliopts pstructs
 
diff --git a/doc/mlr.1 b/doc/mlr.1
index 173572c62..7d4c10c20 100644
--- a/doc/mlr.1
+++ b/doc/mlr.1
@@ -2,12 +2,12 @@
 .\"     Title: mlr
 .\"    Author: [see the "AUTHOR" section]
 .\" Generator: ./mkman.rb
-.\"      Date: 2016-07-28
+.\"      Date: 2016-07-30
 .\"    Manual: \ \&
 .\"    Source: \ \&
 .\"  Language: English
 .\"
-.TH "MILLER" "1" "2016-07-28" "\ \&" "\ \&"
+.TH "MILLER" "1" "2016-07-30" "\ \&" "\ \&"
 .\" -----------------------------------------------------------------
 .\" * Portability definitions
 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -1254,8 +1254,12 @@ Passes through the last n records, optionally by category.
 .RS 0
 .\}
 .nf
-Usage: mlr tee [options]
-xxx write this up please.
+Usage: mlr tee [options] {filename}
+Passes through input records (like mlr cat) but also writes to specified output
+file, using output-format flags from the command line (e.g. --ocsv). See also
+the "tee" keyword within mlr put, which allows data-dependent filenames.
+Options:
+--no-fflush: don't call fflush() after every record.
 .fi
 .if n \{\
 .RE