diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 2037892..e455380 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -94,10 +94,19 @@ Exception only if it is API calling code which is hard to test
 deterministically.
 
 ### Adding new flags to the CLI for testing
-Adding new flags to the CLI for testing is allowed and ENCOURAGED!  For example
-for the skill stuff, we added a flag -D that just dumps all skill directories
-found.  This is useless to the end user, but lets us test the fact that our
-skill directory search was working.
+Adding new flags to the CLI for testing is allowed and ENCOURAGED!  These
+flags serve as **hooks into internal functionality** to enable testing of
+modules that don't have a natural CLI entry point.
+
+For example, for the skill stuff, we added a flag -D that just dumps all skill
+directories found.  This is useless to the end user, but lets us test the fact
+that our skill directory search was working.
+
+**Test flags should be minimal hooks:**
+- They should accept input, call the internal function, and output the result
+- They should NOT contain test logic (assertions, validation, etc.)
+- All test logic belongs in the Bash test scripts in `tests/`
+- The flag's only job is to bridge CLI arguments to the internal function
 
 If you add a new flag for testing you don't need to update the README.md (but
 updating the -h message is still mandatory).