diff --git a/updatebot.py b/updatebot.py
index eacac8c..a94277d 100644
--- a/updatebot.py
+++ b/updatebot.py
@@ -5,6 +5,7 @@ import logging
 import functools
 import os
 import re
+import subprocess
 import tempfile
 import threading
 import urllib.parse
@@ -130,6 +131,10 @@ class BaseProject(abc.ABC, pydantic.BaseModel):
     def apply_updates(self, basedir: Path) -> Iterable[tuple[ImageDef, str]]:
         raise NotImplementedError
 
+    @abc.abstractmethod
+    def resource_diff(self, basedir: Path) -> Optional[str]:
+        raise NotImplementedError
+
 
 class KustomizeProject(BaseProject):
     kind: Literal['kustomize']
@@ -169,6 +174,25 @@ class KustomizeProject(BaseProject):
                 yaml.dump(kustomization, f)
             yield (image, version)
 
+    def resource_diff(self, basedir: Path) -> Optional[str]:
+        path = basedir / self.path
+        cmd = ['kubectl', 'diff', '-k', path]
+        try:
+            p = subprocess.run(
+                cmd,
+                stdin=subprocess.DEVNULL,
+                capture_output=True,
+                check=False,
+                encoding='utf-8',
+            )
+        except FileNotFoundError as e:
+            log.warning('Cannot generate resource diff: %s', e)
+            return None
+        if p.returncode != 0 and not p.stdout:
+            log.error('Failed to generate resource diff: %s', p.stderr)
+            return None
+        return p.stdout
+
 
 Project = KustomizeProject
 
@@ -204,7 +228,11 @@ class RepoConfig(pydantic.BaseModel):
         return data['clone_url']
 
     def create_pr(
-        self, title: str, source_branch: str, target_branch: str
+        self,
+        title: str,
+        source_branch: str,
+        target_branch: str,
+        body: Optional[str] = None,
     ) -> None:
         session = _get_session()
         r = session.post(
@@ -216,6 +244,7 @@ class RepoConfig(pydantic.BaseModel):
                 'title': title,
                 'base': target_branch,
                 'head': source_branch,
+                'body': body,
             },
         )
         log.log(TRACE, '%r', r.content)
@@ -244,10 +273,12 @@ class Arguments:
     projects: list[str]
 
 
-def update_project(repo: git.Repo, project: Project) -> Optional[str]:
+def update_project(
+    repo: git.Repo, project: Project
+) -> tuple[Optional[str], Optional[str]]:
     basedir = Path(repo.working_dir)
     title = None
-    for (image, version) in project.apply_updates(basedir):
+    for image, version in project.apply_updates(basedir):
         log.info('Updating %s to %s', image.name, version)
         if repo.index.diff(None):
             log.debug('Committing changes to %s', project.path)
@@ -261,7 +292,8 @@ def update_project(repo: git.Repo, project: Project) -> Optional[str]:
                     title = c.summary
         else:
             log.info('No changes to commit')
-    return title
+    diff = project.resource_diff(basedir)
+    return title, diff
 
 
 def parse_args() -> Arguments:
@@ -322,29 +354,39 @@ def main() -> None:
             log.debug('Checking out new branch: %s', args.branch_name)
             repo.heads[0].checkout(force=True, B=args.branch_name)
             title = None
+            description = None
             if project.name not in projects:
                 continue
-            title = update_project(repo, project)
+            title, diff = update_project(repo, project)
             if not title:
                 log.info('No changes made')
                 continue
-            repo.head.reference.set_tracking_branch(
-                git.RemoteReference(
-                    repo, f'refs/remotes/origin/{args.branch_name}'
+            if diff:
+                description = (
+                    '<details>\n<summary>Resource diff</summary>\n\n'
+                    f'```diff\n{diff}```\n'
+                    '</details>'
                 )
-            )
             if not args.dry_run:
+                repo.head.reference.set_tracking_branch(
+                    git.RemoteReference(
+                        repo, f'refs/remotes/origin/{args.branch_name}'
+                    )
+                )
                 repo.remote().push(force=True)
                 config.repo.create_pr(
-                    title, args.branch_name, config.repo.branch
+                    title,
+                    args.branch_name,
+                    config.repo.branch,
+                    description,
                 )
             else:
-                log.info(
-                    'Would create PR %s → %s: %s',
-                    config.repo.branch,
-                    args.branch_name,
+                print(
+                    'Would create PR',
+                    f'{args.branch_name} → {config.repo.branch}:',
                     title,
                 )
+                print(description or '')
 
 
 if __name__ == '__main__':