diff --git a/src/library/nft.py b/src/library/nft.py
index b84b88cc636171edf9dc215766d60247be20d59a..b918c8ba8d7ff5b8bd3d96b0b53a83a7ffb24ae8 100644
--- a/src/library/nft.py
+++ b/src/library/nft.py
@@ -26,6 +26,17 @@ from ..sugar import makeDomain, makeField
 
 
 class Gridder(LinearOperator):
+    """
+    Operator computing non-uniform 2D FFTs using ducc0 package.
+
+    Parameters
+    ----------
+    target : Domain, tuple of domains or DomainTuple. This must be a 2D RGSpace.
+    uv : coordinates of the data-points. This is supposed to be a 2D numpy.array
+    eps : requested precision
+    nthreads: @Parras, please fill this
+
+    """
     def __init__(self, target, uv, eps=2e-10, nthreads=1):
         self._capability = self.TIMES | self.ADJOINT_TIMES
         self._target = makeDomain(target)
@@ -67,19 +78,24 @@ class Gridder(LinearOperator):
 
 class FinuFFT(LinearOperator):
     """
-    Operator computing non-uniform FFTs using finufft package
+    Operator computing non-uniform 1D,2D and 3D FFTs using finufft package.
 
     Parameters
     ----------
-    target: must be RGSpace?
-    pos:
-    eps:
+    target : Domain, tuple of domains or DomainTuple.
+        This must be an RGSpace with 1 to 3 dimensions.
+    pos : coordinates of the data-points
+    eps: requested precision
 
     """
     def __init__(self, target, pos, eps=2e-10):
         import finufft
         self._capability = self.TIMES | self.ADJOINT_TIMES
         self._target = makeDomain(target)
+        if not isinstance(self._target[0], RGSpace):
+            raise TypeError("target needs to be an RGSpace")
+        if len(self._target.shape) > 3:
+            raise ValueError("Only 1D, 2D and 3D FFTs are supported by finufft")
         self._domain = DomainTuple.make(UnstructuredDomain((pos.shape[0])))
         self._eps = float(eps)
         dst = np.array(self._target[0].distances)
diff --git a/src/library/special_distributions.py b/src/library/special_distributions.py
index 49b37ca61b94b3d50b5c0ceaa0d401e41c7c1150..ee393648985eb9c813e0bb64e60ab204f9fe8edf 100644
--- a/src/library/special_distributions.py
+++ b/src/library/special_distributions.py
@@ -136,7 +136,6 @@ class UniformOperator(Operator):
         The domain on which the field shall be defined. This is at the same
         time the domain and the target of the operator.
     loc: float
-
     scale: float
 
     """
diff --git a/src/operators/simple_linear_operators.py b/src/operators/simple_linear_operators.py
index 307d5d9a4eca9b46072e9ddf4b3397811cb00861..445b035d4768dd15764dc30dfd3adf9275729fa7 100644
--- a/src/operators/simple_linear_operators.py
+++ b/src/operators/simple_linear_operators.py
@@ -141,7 +141,7 @@ class FieldAdapter(LinearOperator):
 
     Parameters
     ----------
-    tgt : Domain, tuple of Domain, DomainTuple, dict or MultiDomain:
+    tgt : Domain, tuple of domains, DomainTuple, dict or MultiDomain:
         If this is a Domain, tuple of Domain or DomainTuple, this will be the
         operator's target, and its domain will be a MultiDomain consisting of
         its domain with the supplied `name`