diff --git a/AGENTS.md b/AGENTS.md
index 94a9cc02880..acf56c971e4 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -79,6 +79,23 @@ category from the sidebar, one folder under `docs/`, or one page.
 Stop at 20 changed files and open a PR (see `update-content/SKILL.md`).
 Translations go in their own PR per locale and do not count toward the 20.
 
+Mechanical changes that the build or a script checks, such as rewriting links
+or running Prettier, can go in one PR of any size. Keep that PR to the
+mechanical change only, so it stays quick to review.
+
+## Checking a change
+
+Before opening any PR, build the site as CI does. It fails on broken links:
+
+```bash
+yarn generate-library
+yarn generate-adaptors
+yarn build
+```
+
+Broken-anchor warnings do not fail the build, and `main` already has some. Fix
+only the ones your change adds.
+
 ## House style
 
 - Every page has a `title` in its front matter.