diff --git a/app.py b/app.py
index 7ae7cd5..ab38793 100644
--- a/app.py
+++ b/app.py
@@ -1,5 +1,7 @@
 from flask import Flask
 from flask_restx import Api, Resource, fields
+from marshmallow import Schema, fields, validate
+from models import dice_model, ability_model, hp_model
 import random
 
 app = Flask(__name__)
@@ -11,20 +13,18 @@ dice = api.namespace('dice', description='Dice operations')
 ability = api.namespace('ability', description='Ability operations')
 hp = api.namespace('hp', description='HP operations')
 
-dice_model = dice.model('Dice', {
-    'quantity': fields.Integer(required=True, description='The number of dice to roll'),
-    'geometry': fields.Integer(required=True, description='The number of sides on each die'),
-    'discard_lowest': fields.Boolean(required=False, default=False, description='Drop the lowest score')
-})
+dice_model = dice.model('Dice', dice_model)
+ability_model = ability.model('Ability', ability_model)
+hp_model = hp.model('HP', hp_model)
 
-ability_model = ability.model('Ability', {
-    'chartype': fields.String(required=False, default="human", description='Character type')
-})
 
-hp_model = hp.model('HP', {
-    'chartype': fields.String(required=False, default="human", description='Character type'),
-    'conscore': fields.Integer(required=True, description='Conscore')
-})
+class DiceSchema(Schema):
+    quantity = fields.Int(required=True, validate=validate.Range(min=1), description='The number of dice to roll')
+    geometry = fields.Int(required=True, validate=validate.Range(min=2), description='The number of sides on each die')
+    discard_lowest = fields.Bool(default=False, description='Drop the lowest score')
+
+
+dice_schema = DiceSchema()
 
 
 @api.route('/roll/dice', methods=['POST'])
@@ -32,6 +32,9 @@ class RollDice(Resource):
     @dice.expect(dice_model)
     def post(self):
         data = api.payload
+        errors = dice_schema.validate(data)
+        if errors:
+            return errors, 400
         quantity = data.get('quantity')
         geometry = data.get('geometry')
         discard_lowest = data.get('discard_lowest')
@@ -83,16 +86,31 @@ class RollToHit(Resource):
 
 def roll_dices(dice_count, dice_sides, discard_lowest):
     roll_results = []
+    discarded = []
     for _ in range(dice_count):
         roll_results.append(random.randint(1, dice_sides))
     if discard_lowest and len(roll_results) > 0:
+        discarded.append(min(roll_results))
         roll_results.remove(min(roll_results))
 
+    if discarded:
+        net_dice_count = dice_count -1
+        mnemonic = str(dice_count)+"(-1)d"+str(dice_sides)
+    else:
+        mnemonic = str(dice_count)+'d'+str(dice_sides)
+        net_dice_count = dice_count
+
     result = {
-        'die-set': {'quantity': dice_count, 'geometry': dice_sides},
+        'dice-set': {
+            'mnemonic': mnemonic,
+            'min-roll': net_dice_count,
+            'max-roll': dice_sides*net_dice_count
+        },
         'rolls': roll_results,
-        'sum': sum(roll_results)
+        'result': sum(roll_results)
     }
+    if discarded:
+        result['discarded'] = discarded
 
     return result
 
diff --git a/models.py b/models.py
new file mode 100644
index 0000000..37ab988
--- /dev/null
+++ b/models.py
@@ -0,0 +1,23 @@
+from flask_restx import fields
+
+# Common fields
+chartype_field = fields.String(required=False, default="human", description='Character type. Allowed values: "human", '
+                                                                            '"mutant", "android", "robot"')
+
+# Dice model
+dice_model = {
+    'quantity': fields.Integer(required=True, description='The number of dice to roll'),
+    'geometry': fields.Integer(required=True, description='The number of sides on each die'),
+    'discard_lowest': fields.Boolean(required=False, default=False, description='Drop the lowest score')
+}
+
+# Ability model
+ability_model = {
+    'chartype': chartype_field
+}
+
+# Hp model
+hp_model = {
+    'chartype': chartype_field,
+    'conscore': fields.Integer(required=True, description='Conscore')
+}
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..23a2b0e
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,3 @@
+Flask~=3.0.3
+flask-restx~=1.3.0
+marshmallow~=3.21.3
\ No newline at end of file