diff --git a/lib/mbtiles.js b/lib/mbtiles.js
index 8dab716..d667b1c 100644
--- a/lib/mbtiles.js
+++ b/lib/mbtiles.js
@@ -101,6 +101,8 @@ MBTiles.prototype._exists = function(table, callback) {
 };
 
 // DB integrity check.
+//
+// - @param {Function(err)} callback
 MBTiles.prototype._integrity = function(callback) {
     if (typeof callback !== 'function') callback = noop;
 
@@ -108,12 +110,13 @@ MBTiles.prototype._integrity = function(callback) {
         if (!(row && row.integrity_check && row.integrity_check === 'ok')) {
             return callback(new Error('Corrupted database.'));
         } else {
-            return callback(null, true);
+            return callback(null);
         }
     });
 };
 
 // Setup schema, indices, views for a new mbtiles database.
+// - @param {Function(err)} callback
 MBTiles.prototype._setup = function(callback) {
     var mbtiles = this;
     mbtiles._exists('tiles', function(err, exists) {
@@ -130,7 +133,7 @@ MBTiles.prototype._setup = function(callback) {
 // - @param {Number} z tile z coordinate.
 // - @param {Number} x tile x coordinate.
 // - @param {Number} y tile y coordinate.
-// - @param {Function} callback
+// - @param {Function(err, grid, headers)} callback
 MBTiles.prototype.getTile = function(z, x, y, callback) {
     if (typeof callback !== 'function') throw new Error('Callback needed');
     if (!this.open) return callback(new Error('MBTiles not yet loaded'));
@@ -163,7 +166,7 @@ MBTiles.prototype.getTile = function(z, x, y, callback) {
 // - @param {Number} z tile z coordinate
 // - @param {Number} x tile x coordinate
 // - @param {Number} y tile y coordinate
-// - @param {Function} callback
+// - @param {Function(err, grid)} callback
 MBTiles.prototype.getGrid = function(z, x, y, callback) {
     if (typeof callback !== 'function') throw new Error('Callback needed');
     if (!this.open) return callback(new Error('MBTiles not yet loaded'));
@@ -226,9 +229,10 @@ MBTiles.prototype._metadata = function(key, callback) {
         });
 };
 
-// Extend `MBTiles` class with an `info` method for retrieving metadata and
-// performing fallback queries if certain keys (like `bounds`, `minzoom`,
-// `maxzoom`) have not been provided.
+// Obtain metadata from the database. Performing fallback queries if certain
+// keys(like `bounds`, `minzoom`, `maxzoom`) have not been provided.
+//
+// - @param {Function(err, data)} callback
 MBTiles.prototype.getInfo = function(callback) {
     if (typeof callback !== 'function') throw new Error('Callback needed');
     if (!this.open) return callback(new Error('MBTiles not yet loaded'));
@@ -338,7 +342,7 @@ MBTiles.prototype.getInfo = function(callback) {
 
 // Puts the MBTiles tilestore into write mode.
 //
-// - @param {Function} callback
+// - @param {Function(err)} callback
 MBTiles.prototype.startWriting = function(callback) {
     if (typeof callback !== 'function') throw new Error('Callback needed');
     if (!this.open) return callback(new Error('MBTiles not yet loaded'));
@@ -364,7 +368,7 @@ MBTiles.prototype.startWriting = function(callback) {
 
 // (private) Commits the cached changes to the database.
 //
-// - @param {Function} callback
+// - @param {Function(err)} callback
 MBTiles.prototype._commit = function(callback) {
     var mbtiles = this;
     mbtiles._db.serialize(function() {
@@ -453,7 +457,7 @@ MBTiles.prototype._commit = function(callback) {
 
 // Leaves write mode.
 //
-// - @param {Function} callback
+// - @param {Function(err)} callback
 MBTiles.prototype.stopWriting = function(callback) {
     if (typeof callback !== 'function') throw new Error('Callback needed');
     if (!this.open) return callback(new Error('MBTiles not yet loaded'));
@@ -476,7 +480,7 @@ MBTiles.prototype.stopWriting = function(callback) {
 // - @param {Number} x tile x coordinate
 // - @param {Number} y tile y coordinate
 // - @param {Buffer} buffer tile image data
-// - @param {Function} callback
+// - @param {Function(err)} callback
 MBTiles.prototype.putTile = function(z, x, y, data, callback) {
     if (typeof callback !== 'function') throw new Error('Callback needed');
     if (!this.open) return callback(new Error('MBTiles not yet loaded'));
@@ -509,7 +513,7 @@ MBTiles.prototype.putTile = function(z, x, y, data, callback) {
 // - @param {Number} x grid x coordinate
 // - @param {Number} y grid y coordinate
 // - @param {Object} data grid object
-// - @param {Function} callback
+// - @param {Function(err)} callback
 MBTiles.prototype.putGrid = function(z, x, y, data, callback) {
     if (typeof callback !== 'function') throw new Error('Callback needed');
     if (!this.open) return callback(new Error('MBTiles not yet loaded'));