diff --git a/src/scgenerator/spectra.py b/src/scgenerator/spectra.py
index 937e38a..fe73a51 100644
--- a/src/scgenerator/spectra.py
+++ b/src/scgenerator/spectra.py
@@ -229,6 +229,30 @@ def propagation(
     overwrite: bool = False,
     load_parameters: bool = True,
 ) -> Propagation:
+    """
+    Load or create a new propagation
+
+    Parameters
+    ----------
+    file_or_params : PathLike | Parameters:
+        path to existing/new propagation. If `Parameters` type, create a in-memory only propagation
+    params : Parameters | None, optional
+        if creating a new propagation, parameters must be given either as first or second argument
+    bundle_data : bool, optional
+        only used when creating a new simulation
+        copy all external data referenced by the paramters into the archive, by default False
+    overwrite : bool, optional
+        if creating a new propagation, overwrite any existing one, by default False
+    load_parameters : bool, optional
+        when loading a propagation, load the parameters automatically (NOTE: this cannot be done
+        easily after the fact). This is useful if you're laoding a bunch of propagations with
+        identical parameters. Only load the parameters of one of them and ignore it for the rest.
+        by default True
+
+    Returns
+    -------
+    Propagation
+    """
     file = None
     if isinstance(file_or_params, Parameters):
         params = file_or_params