--- a/tools/lint/eslint.yml
+++ b/tools/lint/eslint.yml
@@ -1,8 +1,9 @@
+---
 eslint:
     description: JavaScript linter
     # ESLint infra handles its own path filtering, so just include cwd
     include: ['.']
     exclude: []
     # Make sure these are defined on the same line until the hack
     # in hook_helper.py is fixed.
     extensions: ['js', 'jsm', 'jsx', 'xml', 'html', 'xhtml']

--- a/tools/lint/flake8.yml
+++ b/tools/lint/flake8.yml
@@ -1,8 +1,9 @@
+---
 flake8:
     description: Python linter
     include:
         - layout/tools/reftest
         - python/mozlint
         - security/manager
         - taskcluster
         - testing/firefox-ui

--- a/tools/lint/wpt.yml
+++ b/tools/lint/wpt.yml
@@ -1,7 +1,8 @@
+---
 wpt:
     description: web-platform-tests lint
     include:
         - testing/web-platform/tests
     exclude: []
     type: external
     payload: wpt.wpt:lint

--- a/tools/lint/wpt_manifest.yml
+++ b/tools/lint/wpt_manifest.yml
@@ -1,8 +1,9 @@
+---
 wpt_manifest:
     description: web-platform-tests manifest lint
     include:
         - testing/web-platform/tests
         - testing/web-platform/mozilla/tests
     exclude: []
     type: structured_log
     payload: wpt.wpt_manifest:lint

--- a/tools/lint/yaml.yml
+++ b/tools/lint/yaml.yml
@@ -1,10 +1,13 @@
+---
 yamllint:
     description: YAML linter
     include:
         - .cron.yml
         - python/mozlint/
         - security/nss/.taskcluster.yml
         - taskcluster
+        - testing/mozharness
+        - tools
     extensions: ['yml', 'yaml']
     type: external
     payload: yamllint_:lint