diff --git a/toxcore/tox.h b/toxcore/tox.h
index a828325fd..e674fc654 100644
--- a/toxcore/tox.h
+++ b/toxcore/tox.h
@@ -1776,6 +1776,9 @@ void tox_callback_file_chunk_request(Tox *tox, tox_file_chunk_request_cb *functi
 /**
  * The function type for the `file_receive` callback.
  *
+ * Maximum filename length is TOX_MAX_FILENAME_LENGTH bytes. The filename should generally just be
+ * a file name, not a path with directory names.
+ *
  * The client should acquire resources to be associated with the file transfer.
  * Incoming file transfers start in the PAUSED state. After this callback
  * returns, a transfer can be rejected by sending a TOX_FILE_CONTROL_CANCEL
@@ -1786,6 +1789,10 @@ void tox_callback_file_chunk_request(Tox *tox, tox_file_chunk_request_cb *functi
  *   transfer request.
  * @param file_number The friend-specific file number the data received is
  *   associated with.
+ * @param kind The meaning of the file to be sent.
+ * @param file_size Size in bytes of the file about to be received from the client,
+ *   UINT64_MAX if unknown or streaming.
+ * @param filename_length Size in bytes of the filename.
  */
 typedef void tox_file_recv_cb(Tox *tox, uint32_t friend_number, uint32_t file_number, uint32_t kind,
                               uint64_t file_size, const uint8_t *filename, size_t filename_length, void *user_data);