diff --git a/cmd/mb3dbtool/main.go b/cmd/mb3dbtool/main.go
index f3b9379..2fdc7de 100644
--- a/cmd/mb3dbtool/main.go
+++ b/cmd/mb3dbtool/main.go
@@ -111,15 +111,15 @@ func getConfig() config {
 		panic(errors.New("Could not read port variable: DB_PORT=" + dbPortEnv))
 	}
 	c.DbPort = uint(dbPort)
-	flag.StringVar(&c.DbUser, "user", c.DbUser, "database user name")
-	flag.StringVar(&c.DbPwd, "pwd", c.DbPwd, "database user password")
-	flag.StringVar(&c.DbHost, "host", c.DbHost, "database host")
-	flag.StringVar(&c.DbName, "db", c.DbName, "database name")
-	flag.UintVar(&c.DbPort, "port", c.DbPort, "database port")
-	flag.StringVar(&c.DbConnStr, "connstr", c.DbConnStr, "database connection string")
-	flag.StringVar(&c.gitRepo, "git", c.gitRepo, "git host")
-	flag.StringVar(&c.gitBranch, "branch", c.gitBranch, "git branch")
-	flag.StringVar(&c.dataDir, "dir", c.dataDir, "data directory")
+	flag.StringVar(&c.DbUser, "user", c.DbUser, "database user name. Overwrites environment variable DB_USER")
+	flag.StringVar(&c.DbPwd, "pwd", c.DbPwd, "database user password. Overwrites environment variable DB_PASSWORD")
+	flag.StringVar(&c.DbHost, "host", c.DbHost, "database host. Overwrites environment variable DB_HOST")
+	flag.StringVar(&c.DbName, "db", c.DbName, "database name. Overwrites environment variable DB_NAME")
+	flag.UintVar(&c.DbPort, "port", c.DbPort, "database port. Overwrites environment variable DB_PORT")
+	flag.StringVar(&c.DbConnStr, "connstr", c.DbConnStr, "database connection string. Overwrites environment variable DB_CONN_STRING")
+	flag.StringVar(&c.gitRepo, "git", c.gitRepo, "git repository. Overwrites environment variable MB_GIT_REPO")
+	flag.StringVar(&c.gitBranch, "branch", c.gitBranch, "git branch. Overwrites environment variable MB_GIT_BRANCH")
+	flag.StringVar(&c.dataDir, "dir", c.dataDir, "data directory. Overwrites environment variable MB_DATA_DIRECTORY")
 	flag.Parse()
 	if len(c.gitRepo) > 0 && len(c.dataDir) > 0 {
 		println("Git repo and data directory are set. Using data directory as default and git repo as fallback.")
diff --git a/doc/development.md b/doc/development.md
index f28c499..701e23c 100644
--- a/doc/development.md
+++ b/doc/development.md
@@ -45,6 +45,43 @@ Execute the server:
     
     ./mb3server 
 
+### Building the database tool
+
+To database tool is build with the command:
+
+    > go build -o mb3dbtool cmd/mb3dbtool/main.go 
+
+Get help with:
+
+    > ./mb3dbtool --help
+    Usage of ./mb3dbtool:
+        -branch string
+              git branch. Overwrites environment variable MB_GIT_BRANCH 
+              (default "main")
+        -connstr string
+              database connection string. Overwrites environment variable 
+              DB_CONN_STRING
+        -db string
+              database name. Overwrites environment variable DB_NAME 
+              (default "massbank3")
+        -dir string
+              data directory. Overwrites environment variable MB_DATA_DIRECTORY
+        -git string
+              git repository. Overwrites environment variable MB_GIT_REPO 
+              (default "https://github.com/MassBank/MassBank-data")
+        -host string
+              database host. Overwrites environment variable DB_HOST 
+              (default "localhost")
+        -port uint
+              database port. Overwrites environment variable DB_PORT 
+              (default 27017)
+        -pwd string
+              database user password. Overwrites environment variable 
+              DB_PASSWORD (default "massbank3password")
+        -user string
+              database user name. Overwrites environment variable 
+              DB_USER (default "massbank3")
+
 ### Using docker
 
 To run the server in docker containers you need docker and docker-compose.