diff --git a/accountant/models/accounts.py b/accountant/models/accounts.py
index 51aba35..be6bba8 100644
--- a/accountant/models/accounts.py
+++ b/accountant/models/accounts.py
@@ -21,6 +21,8 @@ from .operations import Operation
 
 
 class Account(db.Model):
+    "Model class to handle accounts."
+    # pylint: disable=invalid-name
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String(200), nullable=False)
     authorized_overdraft = db.Column(db.Integer, nullable=True, default=0)
@@ -31,6 +33,7 @@ class Account(db.Model):
 
     @classmethod
     def query(cls, begin=None, end=None):
+        "Return a query for this class method."
         return db.session.query(
             cls
         ).order_by(
@@ -38,6 +41,8 @@ class Account(db.Model):
         )
 
     def solds(self):
+        "Return the solds of this account."
+        # TODO Alexis Lahouze 2017-05-04 Rename to "balances"
         return db.session.query(
             db.func.sum(Operation.value).label("future"),
             db.func.sum(
@@ -59,6 +64,8 @@ class Account(db.Model):
         ).one()
 
     def balance(self, begin, end):
+        "Return the balance for a specific time period."
+        # TODO Alexis Lahouze 2017-05-04 Rename to "flow" or "cash flow"
         query = db.session.query(
             db.func.sum(
                 db.case(
@@ -89,6 +96,7 @@ class Account(db.Model):
 
     @db.validates('authorized_overdraft')
     def validate_authorized_overdraft(self, key, authorized_overdraft):
+        "Validator for authorized_overdraft : must be negative."
         assert authorized_overdraft <= 0
 
         return authorized_overdraft
diff --git a/accountant/models/operations.py b/accountant/models/operations.py
index 3c3e970..4c4126b 100644
--- a/accountant/models/operations.py
+++ b/accountant/models/operations.py
@@ -22,7 +22,10 @@ import arrow
 from . import db
 
 
+# pylint: disable=too-many-instance-attributes
 class Operation(db.Model):
+    "Class used to handle operations."
+    # pylint: disable=invalid-name
     id = db.Column(db.Integer, primary_key=True)
 
     operation_date = db.Column(
diff --git a/accountant/models/scheduled_operations.py b/accountant/models/scheduled_operations.py
index e760b1a..9535802 100644
--- a/accountant/models/scheduled_operations.py
+++ b/accountant/models/scheduled_operations.py
@@ -26,6 +26,8 @@ from .operations import Operation
 
 
 class ScheduledOperation(db.Model):
+    "Class used to handle scheduled operations."
+    # pylint: disable=invalid-name
     id = db.Column(db.Integer, primary_key=True)
 
     start_date = db.Column(db.Date, nullable=False)
@@ -49,6 +51,7 @@ class ScheduledOperation(db.Model):
         backref=db.backref('scheduled_operation', lazy="dynamic")
     )
 
+    # pylint: disable=too-many-arguments
     def __init__(self, start_date, stop_date, day, frequency, label, value,
                  account_id, category=None):
         self.start_date = start_date
@@ -62,6 +65,7 @@ class ScheduledOperation(db.Model):
 
     @classmethod
     def query(cls):
+        "Return base query for this class."
         return db.session.query(
             cls
         ).order_by(
@@ -71,6 +75,7 @@ class ScheduledOperation(db.Model):
         )
 
     def reschedule(self):
+        "Reschedule a scheduled operation."
         # 1) delete unconfirmed operations for this account.
         db.session.query(
             Operation
diff --git a/accountant/models/users.py b/accountant/models/users.py
index f720c07..bec0d00 100644
--- a/accountant/models/users.py
+++ b/accountant/models/users.py
@@ -28,6 +28,8 @@ from . import db
 
 
 class User(UserMixin, db.Model):
+    "Class used to handle users."
+    # pylint: disable=invalid-name
     id = db.Column(db.Integer, primary_key=True)
     email = db.Column(db.String(200), nullable=False, unique=True, index=True)
     password = db.Column(db.String(100), nullable=True)
@@ -39,22 +41,27 @@ class User(UserMixin, db.Model):
 
     @classmethod
     def query(cls):
+        "Return a query for this class."
         return db.session.query(cls)
 
     @classmethod
     def hash_password(cls, password):
+        "Password hash function."
         return crypt.encrypt(password)
 
     def verify_password(self, password):
+        "Verify password passed in argument with the user's one."
         return crypt.verify(password, self.password)
 
     def generate_auth_token(self):
+        "Generate authentication token used to identify the session."
         serializer = Serializer(app.secret_key)
 
         return serializer.dumps({'id': self.id})
 
     @classmethod
     def verify_auth_token(cls, token):
+        "Verify the authentication token and return the associated user."
         serializer = Serializer(app.config['SECRET_KEY'])
 
         try: