diff --git a/datasette/utils/__init__.py b/datasette/utils/__init__.py
index c6973d06..7fb81f02 100644
--- a/datasette/utils/__init__.py
+++ b/datasette/utils/__init__.py
@@ -1086,12 +1086,35 @@ def _gather_arguments(fn, kwargs):
     return call_with
 
 
+@documented
 def call_with_supported_arguments(fn, **kwargs):
+    """
+    Call ``fn`` with the subset of ``**kwargs`` matching its signature.
+
+    This implements dependency injection: the caller provides all available
+    keyword arguments and the function receives only the ones it declares
+    as parameters.
+
+    :param fn: A callable (sync function)
+    :param kwargs: All available keyword arguments
+    :returns: The return value of ``fn``
+    """
     call_with = _gather_arguments(fn, kwargs)
     return fn(*call_with)
 
 
+@documented
 async def async_call_with_supported_arguments(fn, **kwargs):
+    """
+    Async version of :func:`call_with_supported_arguments`.
+
+    Calls ``await fn(...)`` with the subset of ``**kwargs`` matching its
+    signature.
+
+    :param fn: An async callable
+    :param kwargs: All available keyword arguments
+    :returns: The return value of ``await fn(...)``
+    """
     call_with = _gather_arguments(fn, kwargs)
     return await fn(*call_with)
 
diff --git a/docs/internals.rst b/docs/internals.rst
index 704643cc..829b4dd4 100644
--- a/docs/internals.rst
+++ b/docs/internals.rst
@@ -2115,6 +2115,43 @@ Note that the space character is a special case: it will be replaced with a ``+`
 
 .. autofunction:: datasette.utils.tilde_decode
 
+.. _internals_utils_call_with_supported_arguments:
+
+call_with_supported_arguments(fn, **kwargs)
+-------------------------------------------
+
+Call ``fn``, passing it only those keyword arguments that match its function signature. This implements a dependency injection pattern - the caller provides all available arguments, and the function receives only the ones it declares as parameters.
+
+This is useful in plugins that want to define callback functions that only declare the arguments they need. For example:
+
+.. code-block:: python
+
+    from datasette.utils import call_with_supported_arguments
+
+
+    def my_callback(request, datasette): ...
+
+
+    # This will pass only request and datasette, ignoring other kwargs:
+    call_with_supported_arguments(
+        my_callback,
+        request=request,
+        datasette=datasette,
+        database=database,
+        table=table,
+    )
+
+.. autofunction:: datasette.utils.call_with_supported_arguments
+
+.. _internals_utils_async_call_with_supported_arguments:
+
+await async_call_with_supported_arguments(fn, **kwargs)
+-------------------------------------------------------
+
+Async version of :ref:`call_with_supported_arguments <internals_utils_call_with_supported_arguments>`. Use this for ``async def`` callback functions.
+
+.. autofunction:: datasette.utils.async_call_with_supported_arguments
+
 .. _internals_tracer:
 
 datasette.tracer