diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..205e77e
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,6 @@
+# Purpose
+This is a C# exercise repository to explore creating class and sequence diagrams with mermaid, in order to understand an unfamiliar codebase, perform continuous architecture review, or review code generated by coding agents.
+
+# Generating mermaid diagrams and reviewing syntax
+
+On linux and mac, the `mmdc` executable is available to create svg diagrams and check syntax. On windows, use the mmdc binary in `./node_modules/bin/mmdc` .