diff --git a/.toys/generate.rb b/.toys/generate.rb
new file mode 100644
index 000000000..ce5cf3f41
--- /dev/null
+++ b/.toys/generate.rb
@@ -0,0 +1,35 @@
+desc "Run standard Google client generation."
+
+optional_arg :api, desc: "API name (optional). Generates all APIs if omitted."
+optional_arg :version, desc: "API version. Required if the API name is given."
+
+include :bundler, gemfile_path: "#{context_directory}/google-apis-generator/Gemfile"
+include :exec, e: true
+
+def run
+  Dir.chdir "#{context_directory}/google-apis-generator"
+  case api
+  when "clean"
+    exec ["bin/generate-api", "gen",
+          "#{context_directory}/generated",
+          "--clean"]
+  when nil
+    p exec ["bin/generate-api", "gen",
+          "#{context_directory}/generated",
+          "--from-discovery",
+          "--no-preferred-only",
+          "--spot-check",
+          "--names=#{context_directory}/api_names.yaml",
+          "--names-out=#{context_directory}/api_names_out.yaml"],
+         in: [:string, "a\n"]
+  else
+    raise "Version is required if an API is given" unless version
+    exec ["bin/generate-api", "gen",
+          "#{context_directory}/generated",
+          "--api=#{api}.#{version}",
+          "--spot-check",
+          "--names=#{context_directory}/api_names.yaml",
+          "--names-out=#{context_directory}/api_names_out.yaml"],
+         in: [:string, "a\n"]
+  end
+end
diff --git a/script/synth.rb b/script/synth.rb
index 89d382b23..f316d35c7 100755
--- a/script/synth.rb
+++ b/script/synth.rb
@@ -9,6 +9,12 @@ def execute cmd
   abort unless system cmd
 end
 
+# In an autosynth (multi-library) run, a previous library synth may have
+# created a new library. If so, autosynth doesn't clean up those newly created
+# files (i.e. it runs git reset --hard but not git clean). Do that ourselves,
+# so any previously created files don't pollute this and subsequent synth runs.
+execute "git clean -df"
+
 Dir.chdir "google-apis-generator"
 
 execute "bundle install"