diff --git a/README.md b/README.md
index 3822a3e..0060da8 100644
--- a/README.md
+++ b/README.md
@@ -188,6 +188,18 @@ Prints the review to CI logs without posting to the PR. Useful for testing promp
 | `update-existing` | No | `true` | Delete previous review from same bot before posting. Accepts: true/1/yes or false/0/no |
 | `version` | No | `latest` | review-bot version to install |
 
+## Runner Requirements
+
+The composite action requires these tools on the runner:
+
+| Tool | Used For |
+|------|----------|
+| `python3` | JSON parsing during version detection |
+| `sha256sum` | Checksum verification of downloaded binary |
+| `curl` | Downloading releases and querying the API |
+
+All three are pre-installed on `ubuntu-*` runners (e.g. `ubuntu-24.04`). If you use a custom runner image, ensure these are available.
+
 ## How Review Cleanup Works
 
 When `reviewer-name` is set, the bot embeds a hidden sentinel in each review: