got it working with vars, now try the URLs

Jenkinsfile

@@ -40,7 +40,7 @@ pipeline {
           reportName: 'Test Results',
           reportTitles: 'Test Coverage'])
         cucumber buildStatus: 'UNCHANGED', customCssFiles: '', customJsFiles: '', failedFeaturesNumber: -1, failedScenariosNumber: -1, failedStepsNumber: -1, fileIncludePattern: '**/cucumber.json', pendingStepsNumber: -1, skippedStepsNumber: -1, sortingMethod: 'ALPHABETICAL', undefinedStepsNumber: -1
-        mattermostSend channel: 'git-messages', color: 'good', message: "Finished building ${JOB_NAME} - ${BUILD_NUMBER} ${DB_NAME}", text: 'Build Finished'
+        mattermostSend channel: 'git-messages', color: 'good', message: "Finished building ${JOB_URL} - ${BUILD_URL}", text: 'Build Finished'
       }
     }
   }