diff --git a/micrometer-commons/src/main/java/io/micrometer/common/docs/KeyName.java b/micrometer-commons/src/main/java/io/micrometer/common/docs/KeyName.java
index 23e1e7ac73..d71dbebf1e 100644
--- a/micrometer-commons/src/main/java/io/micrometer/common/docs/KeyName.java
+++ b/micrometer-commons/src/main/java/io/micrometer/common/docs/KeyName.java
@@ -62,4 +62,13 @@ default KeyValue withValue(String value, Predicate<Object> validator) {
      */
     String asString();
 
+    /**
+     * Whether this key is required to be present in the instrumentation. This can be
+     * checked in a test of the instrumentation.
+     * @return whether this key is required
+     */
+    default boolean isRequired() {
+        return true;
+    }
+
 }
diff --git a/micrometer-observation-test/src/test/java/io/micrometer/observation/tck/TestObservationRegistryAssertTests.java b/micrometer-observation-test/src/test/java/io/micrometer/observation/tck/TestObservationRegistryAssertTests.java
index f2f90beacd..d2d92b9950 100644
--- a/micrometer-observation-test/src/test/java/io/micrometer/observation/tck/TestObservationRegistryAssertTests.java
+++ b/micrometer-observation-test/src/test/java/io/micrometer/observation/tck/TestObservationRegistryAssertTests.java
@@ -356,6 +356,19 @@ enum MyKeyName implements KeyName {
             public String asString() {
                 return "foo";
             }
+        },
+
+        MAYBE_SOMETHING {
+
+            @Override
+            public String asString() {
+                return "maybe.something";
+            }
+
+            @Override
+            public boolean isRequired() {
+                return false;
+            }
         }
 
     }