diff --git a/include/weaseljson.h b/include/weaseljson.h
index 4e01ec7..ce2384b 100644
--- a/include/weaseljson.h
+++ b/include/weaseljson.h
@@ -9,11 +9,15 @@ struct WeaselJsonCallbacks {
   void (*on_begin_object)(void *data);
   void (*on_end_object)(void *data);
   void (*on_begin_string)(void *data);
+  /** May be called multiple times per string if not all string data is
+   * available yet. The string data provided is unescaped. */
   void (*on_string_data)(void *data, const char *buf, int len);
   void (*on_end_string)(void *data);
   void (*on_begin_array)(void *data);
   void (*on_end_array)(void *data);
   void (*on_begin_number)(void *data);
+  /** May be called multiple times per number if not all number data is
+   * available yet */
   void (*on_number_data)(void *data, const char *buf, int len);
   void (*on_end_number)(void *data);
   void (*on_true_literal)(void *data);
@@ -25,7 +29,7 @@ enum WeaselJsonStatus {
   /** Accept input */
   WeaselJson_OK,
   /** Consumed all available input. Call WeaselJsonParser_parse with more data
-     to provide more input, or call with length 0 to indicate end of data*/
+     to provide more input, or call with length 0 to indicate end of data */
   WeaselJson_AGAIN,
   /** Invalid json */
   WeaselJson_REJECT,
@@ -35,9 +39,12 @@ enum WeaselJsonStatus {
 
 typedef struct WeaselJsonParser WeaselJsonParser;
 
-/** Increasing stack size increases memory usage but also increases the depth of
- * nested json accepted. */
-WeaselJsonParser *WeaselJsonParser_create(int stackSize);
+/** Create a parser. Increasing stack size increases memory usage but also
+ * increases the depth of nested json accepted. `callbacks` and `data` must
+ * outlive the returned parser. */
+WeaselJsonParser *WeaselJsonParser_create(int stackSize,
+                                          const WeaselJsonCallbacks *callbacks,
+                                          void *data);
 
 /** Restore the parser to its newly-created state */
 void WeaselJsonParser_reset(WeaselJsonParser *parser);