diff --git a/placement-api-ref/ext/__init__.py b/placement-api-ref/ext/__init__.py
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/tools/placement_api_docs.py b/placement-api-ref/ext/validator.py
similarity index 84%
rename from tools/placement_api_docs.py
rename to placement-api-ref/ext/validator.py
index bec5d2594261..44a4cef36af3 100644
--- a/tools/placement_api_docs.py
+++ b/placement-api-ref/ext/validator.py
@@ -12,7 +12,6 @@
 """Test to see if docs exists for routes and methods in the placement API."""
 
 import os
-import sys
 
 from nova.api.openstack.placement import handler
 
@@ -27,11 +26,14 @@ def _header_line(map_entry):
     return line
 
 
-def inspect_doc(doc_files):
+def inspect_doc(app):
     """Load up doc_files and see if any routes are missing.
 
     The routes are defined in handler.ROUTE_DECLARATIONS.
     """
+    doc_files = [os.path.join(app.srcdir, file)
+                 for file in os.listdir(app.srcdir) if file.endswith(".inc")]
+
     routes = []
     for route in sorted(handler.ROUTE_DECLARATIONS, key=len):
         # Skip over the '' route.
@@ -56,16 +58,11 @@ def inspect_doc(doc_files):
             missing_lines.append(line)
 
     if missing_lines:
-        print('Documentation likely missing for the following routes:')
+        msg = ['Documentation likely missing for the following routes:', '']
         for line in missing_lines:
-            print(line)
-        return 1
-
-    return 0
+            msg.append(line)
+        raise ValueError('\n'.join(msg))
 
 
-if __name__ == '__main__':
-    path = sys.argv[1]
-    doc_files = [os.path.join(path, file)
-                 for file in os.listdir(path) if file.endswith(".inc")]
-    sys.exit(inspect_doc(doc_files))
+def setup(app):
+    app.connect('builder-inited', inspect_doc)
diff --git a/placement-api-ref/source/conf.py b/placement-api-ref/source/conf.py
index f52d3fdbd0c6..d4766be180de 100644
--- a/placement-api-ref/source/conf.py
+++ b/placement-api-ref/source/conf.py
@@ -22,12 +22,17 @@
 # All configuration values have a default; values that are commented out
 # serve to show the default.
 
+import os
+import sys
+
 from nova.version import version_info
 
+sys.path.insert(0, os.path.abspath('../'))
 
 extensions = [
     'openstackdocstheme',
     'os_api_ref',
+    'ext.validator',
 ]
 
 # -- General configuration ----------------------------------------------------
diff --git a/tox.ini b/tox.ini
index a6e582864472..e1c0823a5ce9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -182,8 +182,6 @@ description =
   Generate the Placement API ref. Called from CI scripts to test and publish to developer.openstack.org.
 deps = {[testenv:docs]deps}
 commands =
-  # Check that all placement api routes are in the documentation
-  python tools/placement_api_docs.py placement-api-ref/source/
   rm -rf placement-api-ref/build
   sphinx-build -W -b html -d placement-api-ref/build/doctrees placement-api-ref/source placement-api-ref/build/html