diff --git a/astropy/cosmology/parameter/_converter.py b/astropy/cosmology/parameter/_converter.py
index f91b0bc881e..59a170e6bd3 100644
--- a/astropy/cosmology/parameter/_converter.py
+++ b/astropy/cosmology/parameter/_converter.py
@@ -2,19 +2,21 @@
 
 from __future__ import annotations
 
-from collections.abc import Callable
-from typing import TYPE_CHECKING, Any, TypeAlias, TypeVar, overload
+from typing import TYPE_CHECKING, Any, TypeAlias, overload
 
 import astropy.units as u
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
+    from numpy.typing import NDArray
+
     from astropy.cosmology import Cosmology, Parameter
 
+    _FValidateCallable: TypeAlias = Callable[[Cosmology, Parameter, Any], Any]
+
 __all__: list[str] = []
 
-# Callable[[Cosmology, Parameter, Any], Any]
-_FValidateCallable: TypeAlias = Callable[["Cosmology", "Parameter", Any], Any]
-T = TypeVar("T")
 
 _REGISTRY_FVALIDATORS: dict[str, _FValidateCallable] = {}
 
@@ -92,14 +94,16 @@ def _validate_with_unit(cosmology: Cosmology, param: Parameter, value: Any) -> A
 
 
 @_register_validator("float")
-def _validate_to_float(cosmology: Cosmology, param: Parameter, value: Any) -> Any:
+def _validate_to_float(cosmology: Cosmology, param: Parameter, value: Any) -> float:
     """Parameter value validator with units, and converted to float."""
     value = _validate_with_unit(cosmology, param, value)
     return float(value)
 
 
 @_register_validator("scalar")
-def _validate_to_scalar(cosmology: Cosmology, param: Parameter, value: Any) -> Any:
+def _validate_to_scalar(
+    cosmology: Cosmology, param: Parameter, value: Any
+) -> NDArray[Any]:
     """"""
     value = _validate_with_unit(cosmology, param, value)
     if not value.isscalar:
@@ -108,7 +112,7 @@ def _validate_to_scalar(cosmology: Cosmology, param: Parameter, value: Any) -> A
 
 
 @_register_validator("non-negative")
-def _validate_non_negative(cosmology: Cosmology, param: Parameter, value: Any) -> Any:
+def _validate_non_negative(cosmology: Cosmology, param: Parameter, value: Any) -> float:
     """Parameter value validator where value is a positive float."""
     value = _validate_to_float(cosmology, param, value)
     if value < 0.0:
diff --git a/astropy/cosmology/parameter/_core.py b/astropy/cosmology/parameter/_core.py
index 872fab69c12..2c1d800e2af 100644
--- a/astropy/cosmology/parameter/_core.py
+++ b/astropy/cosmology/parameter/_core.py
@@ -5,25 +5,26 @@
 __all__ = ["Parameter"]
 
 import copy
-from collections.abc import Callable
 from dataclasses import KW_ONLY, dataclass, field, fields, is_dataclass, replace
 from enum import Enum, auto
-from typing import TYPE_CHECKING, Any, Generic, TypeAlias, TypeVar, overload
+from typing import TYPE_CHECKING, Any, Generic, TypeVar, overload
 
 import astropy.units as u
 
 from ._converter import _REGISTRY_FVALIDATORS, _register_validator
 
 if TYPE_CHECKING:
-    from collections.abc import Sequence
+    from collections.abc import Callable, Sequence
+    from typing import TypeAlias
 
     from typing_extensions import Self
 
     from astropy.cosmology import Cosmology
 
+    _FValidateCallable: TypeAlias = Callable[[Cosmology, "Parameter", Any], "_VT"]
 
-_VT = TypeVar("_VT")  # the type of the VParameter value
-_FValidateCallable: TypeAlias = Callable[["Cosmology", "Parameter", Any], _VT]
+
+_VT = TypeVar("_VT")  # the type of the VParameter value. Required at runtime.
 
 
 class Sentinel(Enum):
@@ -171,14 +172,12 @@ def __set_name__(self, cosmo_cls: type, name: str | None) -> None:
     # descriptor and property-like methods
 
     @overload
-    def __get__(self, cosmology: None, cosmo_cls: Any) -> Parameter: ...
+    def __get__(self, cosmology: None, cosmo_cls: Any) -> Self: ...
 
     @overload
     def __get__(self, cosmology: Cosmology, cosmo_cls: Any) -> _VT: ...
 
-    def __get__(
-        self, cosmology: Cosmology | None, cosmo_cls: Any = None
-    ) -> Parameter | _VT:
+    def __get__(self, cosmology: Cosmology | None, cosmo_cls: Any = None) -> Self | _VT:
         # Get from class
         if cosmology is None:
             # If the Parameter is being set as part of a dataclass constructor, then we
@@ -301,7 +300,7 @@ def clone(self, **kw: Any) -> Self:
 
         Parameters
         ----------
-        **kw : Any
+        **kw : dict, optional
             Passed to constructor. The current values, eg. ``fvalidate`` are
             used as the default values, so an empty ``**kw`` is an exact copy.