fix: mark database field as required in the firestore prebuilt tools (#959)

Env variables cannot be used as optional parameters, hence marking
database field as required.

cmd/root.go

@@ -190,7 +190,7 @@ func NewCommand(opts ...Option) *Command {
 	flags.BoolVar(&cmd.cfg.TelemetryGCP, "telemetry-gcp", false, "Enable exporting directly to Google Cloud Monitoring.")
 	flags.StringVar(&cmd.cfg.TelemetryOTLP, "telemetry-otlp", "", "Enable exporting using OpenTelemetry Protocol (OTLP) to the specified endpoint (e.g. 'http://127.0.0.1:4318')")
 	flags.StringVar(&cmd.cfg.TelemetryServiceName, "telemetry-service-name", "toolbox", "Sets the value of the service.name resource attribute for telemetry data.")
-	flags.StringVar(&cmd.prebuiltConfig, "prebuilt", "", "Use a prebuilt tool configuration by source type. Cannot be used with --tools-file. Allowed: 'alloydb-postgres', 'bigquery', 'cloud-sql-mysql', 'cloud-sql-postgres', 'cloud-sql-mssql', 'postgres', 'spanner', 'spanner-postgres'.")
+	flags.StringVar(&cmd.prebuiltConfig, "prebuilt", "", "Use a prebuilt tool configuration by source type. Cannot be used with --tools-file. Allowed: 'alloydb-postgres', 'bigquery', 'cloud-sql-mysql', 'cloud-sql-postgres', 'cloud-sql-mssql', 'firestore', 'postgres', 'spanner', 'spanner-postgres'.")
 	flags.BoolVar(&cmd.cfg.Stdio, "stdio", false, "Listens via MCP STDIO instead of acting as a remote HTTP server.")
 	flags.BoolVar(&cmd.cfg.DisableReload, "disable-reload", false, "Disables dynamic reloading of tools file.")
 

internal/prebuiltconfigs/tools/firestore.yaml

@@ -2,7 +2,7 @@ sources:
   firestore-source:
     kind: firestore
     project: ${FIRESTORE_PROJECT}
-    database: ${FIRESTORE_DATABASE}  # Optional, defaults to "(default)" if not specified
+    database: ${FIRESTORE_DATABASE}
 
 tools:
   firestore-get-documents: