diff --git a/corrlib/integrity.py b/corrlib/integrity.py
index 74386f4..f5b2300 100644
--- a/corrlib/integrity.py
+++ b/corrlib/integrity.py
@@ -12,6 +12,20 @@ from typing import Any
 
 
 def has_valid_times(result: pd.Series) -> bool:
+    """
+    Check, whether the result at hand has time-stamps that are sensible:
+    A recored is created first, then updated, with both times laying in the past.
+
+    Parameters
+    ----------
+    result: pd.Series
+        The result to check
+
+    Returns
+    -------
+    b: bool
+        True, if the timestamps make sense.
+    """
     # we expect created_at <= updated_at <= now
     created_at = dt.datetime.fromisoformat(result['created_at'])
     updated_at = dt.datetime.fromisoformat(result['updated_at'])
@@ -22,15 +36,41 @@ def has_valid_times(result: pd.Series) -> bool:
     return True
 
 def are_keys_unique(db: Path, table: str, col: str) -> bool:
+    """
+    Check whether the strings listed in a column of a given table are unique.
+
+    Parameters
+    ----------
+    db: Path
+        The database to check.
+    table: str
+        The table to check.
+    col: str
+        The column to be checked for uniqueness.
+
+    Returns
+    -------
+    b: bool
+        True, if the strings are unique.
+    """
     conn = sqlite3.connect(db)
     c = conn.cursor()
-    c.execute(f"SELECT COUNT( DISTINCT CAST(path AS nvarchar(4000))), COUNT({col}) FROM {table};")
+    c.execute(f"SELECT COUNT( DISTINCT CAST({col} AS nvarchar(4000))), COUNT({col}) FROM {table};")
     results = c.fetchall()[0]
     conn.close()
     return bool(results[0] == results[1])
 
 
 def check_db_integrity(path: Path) -> None:
+    """
+    Check intergrity of the database by checking the uniqueness of the record keys used to load the records
+    and ensuring that the timestamps of each record is sensible. Throws an error, if issues are detected.
+
+    Parameters
+    ----------
+    path: Path
+        Path to the backlog-library to check.
+    """
     db = get_db_file(path)
 
     if not are_keys_unique(path / db, 'backlogs', 'path'):
@@ -47,6 +87,17 @@ def check_db_integrity(path: Path) -> None:
 
 
 def _check_db2paths(path: Path, meas_paths: list[str]) -> None:
+    """
+    Check whether for each record in the given by meas_paths, we can find the data in the file as we expect.
+    Also check, whether there are unreachable records in the files. If either of the issues arise, throws an error.
+
+    Parameters
+    ----------
+    path: Path
+        Path to the backlog-library to check.
+    meas_paths: list[str]
+        List of measurement paths to check.
+    """
     needed_data: dict[str, list[str]] = {}
     for mpath in meas_paths:
         file = mpath.split("::")[0]
@@ -72,6 +123,15 @@ def _check_db2paths(path: Path, meas_paths: list[str]) -> None:
 
 
 def check_db_file_links(path: Path) -> None:
+    """
+    Check whether for each record in the given correlator library, we can find the data in the file as we expect.
+    Also check, whether there are unreachable records in the files. If either of the issues arise, throws an error.
+
+    Parameters
+    ----------
+    path: Path
+        Path to the backlog-library to check.
+    """
     db = get_db_file(path)
     search_expr = "SELECT path FROM 'backlogs'"
     conn = sqlite3.connect(path / db)
@@ -80,6 +140,14 @@ def check_db_file_links(path: Path) -> None:
 
 
 def check_path_and_config(path: Path) -> None:
+    """
+    Check whether the given path exists and the cinfigureation file can be found.
+
+    Parameters
+    ----------
+    path: Path
+        Path to the backlog-library to check.
+    """
     if not os.path.exists(path):
         raise FileNotFoundError(f"Corrlib path {path} does not exist.")
     config_path = path / CONFIG_FILENAME
@@ -88,6 +156,14 @@ def check_path_and_config(path: Path) -> None:
 
 
 def check_config_validity(path: Path) -> None:
+    """
+    Check whether the configuration file of the given corrlib-dataset path is valid.
+
+    Parameters
+    ----------
+    path: Path
+        Path to the backlog-library to check.
+    """
     config = ConfigParser()
     config_path = path / CONFIG_FILENAME
     if os.path.exists(config_path):
@@ -107,8 +183,20 @@ def check_config_validity(path: Path) -> None:
         if not all(has_path_opts):
             raise ValueError("One of the options in the 'path' section  ('db', 'projects_path', 'archive_path', 'toml_imports_path', 'import_scripts_path') is missing.")
 
+    has_paths = [os.path.exists(path / config.get('paths', opt)) for opt in path_opts]
+    if not all(has_paths):
+        raise FileNotFoundError("one of the paths needed by the configuration file is not present.")
+
 
 def full_integrity_check(path: Path) -> None:
+    """
+    Aggregate all checks for easy validation of the backlog-library.
+
+    Parameters
+    ----------
+    path: Path
+        Path to the backlog-library to check.
+    """
     check_path_and_config(path)
     print("Path and config-file exist:\t✅")
     check_config_validity(path)