diff --git a/src/spanner/src/observability/exporter.rs b/src/spanner/src/observability/exporter.rs
index 3c37213e1c..3ddba1f06c 100644
--- a/src/spanner/src/observability/exporter.rs
+++ b/src/spanner/src/observability/exporter.rs
@@ -325,16 +325,11 @@ fn key_values_to_metric_labels<'a>(
 }
 
 pub(crate) fn resource_to_monitored_resource(resource: &Resource) -> MonitoredResource {
-    let mut labels = HashMap::new();
-    for (key, val) in resource.iter() {
-        let key_str = key.as_str();
-        match key_str {
-            "instance_id" | "location" | "instance_config" | "client_hash" => {
-                labels.insert(key_str.to_string(), value_to_string(val));
-            }
-            _ => {}
-        }
-    }
+    let labels: HashMap<String, String> = resource
+        .iter()
+        .filter(|(key, _)| is_monitored_resource_label(key.as_str()))
+        .map(|(key, value)| (key.as_str().to_string(), value_to_string(value)))
+        .collect();
 
     MonitoredResource::new()
         .set_type(SPANNER_RESOURCE_TYPE.to_string())
@@ -524,33 +519,48 @@ mod tests {
 
         let monitored_res = super::resource_to_monitored_resource(&resource);
 
-        assert_eq!(monitored_res.r#type, "spanner_instance_client");
         assert_eq!(
-            monitored_res.labels.get("instance_id").map(|s| s.as_str()),
-            Some("my-instance")
+            monitored_res.r#type, "spanner_instance_client",
+            "Resource type must be spanner_instance_client"
+        );
+        assert_eq!(
+            monitored_res.labels.get("project_id").map(String::as_str),
+            Some("my-project"),
+            "MonitoredResource must contain project_id"
+        );
+        assert_eq!(
+            monitored_res.labels.get("instance_id").map(String::as_str),
+            Some("my-instance"),
+            "MonitoredResource must contain instance_id"
         );
         assert_eq!(
-            monitored_res.labels.get("location").map(|s| s.as_str()),
-            Some("us-central1")
+            monitored_res.labels.get("location").map(String::as_str),
+            Some("us-central1"),
+            "MonitoredResource must contain location"
         );
         assert_eq!(
             monitored_res
                 .labels
                 .get("instance_config")
-                .map(|s| s.as_str()),
-            Some("regional-us-central1")
+                .map(String::as_str),
+            Some("regional-us-central1"),
+            "MonitoredResource must contain instance_config"
         );
         assert_eq!(
-            monitored_res.labels.get("client_hash").map(|s| s.as_str()),
-            Some("abc1234")
+            monitored_res.labels.get("client_hash").map(String::as_str),
+            Some("abc1234"),
+            "MonitoredResource must contain client_hash"
         );
 
-        // project_id must be excluded
-        assert!(!monitored_res.labels.contains_key("project_id"));
-
         // Unrelated OpenTelemetry resource attributes must be filtered out
-        assert!(!monitored_res.labels.contains_key("service.name"));
-        assert!(!monitored_res.labels.contains_key("telemetry.sdk.version"));
+        assert!(
+            !monitored_res.labels.contains_key("service.name"),
+            "service.name must be filtered out"
+        );
+        assert!(
+            !monitored_res.labels.contains_key("telemetry.sdk.version"),
+            "telemetry.sdk.version must be filtered out"
+        );
     }
 
     #[test]
diff --git a/src/spanner/src/observability/mock_tests.rs b/src/spanner/src/observability/mock_tests.rs
index 1c98576036..4771b477d8 100644
--- a/src/spanner/src/observability/mock_tests.rs
+++ b/src/spanner/src/observability/mock_tests.rs
@@ -52,6 +52,7 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 use tokio::sync::mpsc::{Receiver, channel};
 use tokio::task::JoinHandle;
 
+const TEST_PROJECT: &str = "test-project";
 const TEST_CLIENT_UID: &str = "test-uid-12345";
 const TEST_CLIENT_HASH: &str = "abc1234";
 const TEST_DATABASE: &str = "test-database";
@@ -226,6 +227,14 @@ async fn streaming_sql_happy_path_records_all_metrics_and_time_series() -> anyho
             monitored_resource.r#type, "spanner_instance_client",
             "Resource type must be spanner_instance_client"
         );
+        assert_eq!(
+            monitored_resource
+                .labels
+                .get("project_id")
+                .map(String::as_str),
+            Some(TEST_PROJECT),
+            "MonitoredResource must contain project_id"
+        );
         assert_eq!(
             monitored_resource
                 .labels
@@ -2183,7 +2192,7 @@ async fn setup_mock_client_with_metrics(
 
     let resource = Resource::builder()
         .with_attributes([
-            KeyValue::new("project_id", "test-project"),
+            KeyValue::new("project_id", TEST_PROJECT),
             KeyValue::new("instance_id", TEST_INSTANCE),
             KeyValue::new("location", TEST_LOCATION),
             KeyValue::new("instance_config", TEST_INSTANCE_CONFIG),