updates based on review feedback
diff --git a/docs/x509.rst b/docs/x509.rst
index f66178a..4246862 100644
--- a/docs/x509.rst
+++ b/docs/x509.rst
@@ -736,12 +736,19 @@
 
         :type: :class:`ObjectIdentifier`
 
-        Either :data:`OID_OCSP` or :data:`OID_CA_ISSUERS`
+        The access method defines what the ``access_location`` means. It must
+        be either :data:`OID_OCSP` or :data:`OID_CA_ISSUERS`. If it is
+        :data:`OID_OCSP` the access location will be where to obtain OCSP
+        information for the certificate. If it is :data:`OID_CA_ISSUERS` the
+        access location will provide additional information about the issuing
+        certificate.
 
     .. attribute:: access_location
 
         :type: :class:`GeneralName`
 
+        Where to access the information defined by the access method.
+
 Object Identifiers
 ~~~~~~~~~~~~~~~~~~
 
diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index 2bbd14d..2733709 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -67,8 +67,8 @@
     "1.3.6.1.5.5.7.1.1": "authorityInfoAccess",
     "1.3.6.1.5.5.7.1.11": "subjectInfoAccess",
     "1.3.6.1.5.5.7.48.1.5": "OCSPNoCheck",
-    "1.3.6.1.5.5.7.48.2": "caIssuers",
     "1.3.6.1.5.5.7.48.1": "OCSP",
+    "1.3.6.1.5.5.7.48.2": "caIssuers",
 }
 
 
@@ -428,7 +428,9 @@
 class AccessDescription(object):
     def __init__(self, access_method, access_location):
         if not (access_method == OID_OCSP or access_method == OID_CA_ISSUERS):
-            raise TypeError("access_method must be OID_OCSP or OID_CA_ISSUERS")
+            raise ValueError(
+                "access_method must be OID_OCSP or OID_CA_ISSUERS"
+            )
 
         if not isinstance(access_location, GeneralName):
             raise TypeError("access_location must be a GeneralName")
diff --git a/tests/test_x509_ext.py b/tests/test_x509_ext.py
index 711b6b7..0e5cab5 100644
--- a/tests/test_x509_ext.py
+++ b/tests/test_x509_ext.py
@@ -992,7 +992,7 @@
 
 class TestAccessDescription(object):
     def test_invalid_access_method(self):
-        with pytest.raises(TypeError):
+        with pytest.raises(ValueError):
             x509.AccessDescription("notanoid", x509.DNSName(u"test"))
 
     def test_invalid_access_location(self):