diff --git a/src/main/java/org/apache/solr/mcp/server/collection/CollectionService.java b/src/main/java/org/apache/solr/mcp/server/collection/CollectionService.java
index 48ec56d3..f42a15fc 100644
--- a/src/main/java/org/apache/solr/mcp/server/collection/CollectionService.java
+++ b/src/main/java/org/apache/solr/mcp/server/collection/CollectionService.java
@@ -24,8 +24,8 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import io.micrometer.observation.annotation.Observed;
 import java.io.IOException;
+import java.time.Instant;
 import java.util.ArrayList;
-import java.util.Date;
 import java.util.List;
 import org.apache.solr.client.solrj.SolrClient;
 import org.apache.solr.client.solrj.SolrRequest;
@@ -428,7 +428,7 @@ public SolrMetrics getCollectionStats(
 		QueryResponse statsResponse = solrClient.query(actualCollection, new SolrQuery(ALL_DOCUMENTS_QUERY).setRows(0));
 
 		return new SolrMetrics(buildIndexStats(lukeResponse), buildQueryStats(statsResponse),
-				fetchCacheMetrics(actualCollection), fetchHandlerMetrics(actualCollection), new Date());
+				fetchCacheMetrics(actualCollection), fetchHandlerMetrics(actualCollection), Instant.now());
 	}
 
 	/**
@@ -967,10 +967,10 @@ public SolrHealthStatus checkHealth(@McpToolParam(description = "Solr collection
 					new SolrQuery(ALL_DOCUMENTS_QUERY).setRows(0));
 
 			return new SolrHealthStatus(true, null, pingResponse.getElapsedTime(),
-					statsResponse.getResults().getNumFound(), new Date(), actualCollection, null, null);
+					statsResponse.getResults().getNumFound(), Instant.now(), actualCollection, null, null);
 
 		} catch (Exception e) {
-			return new SolrHealthStatus(false, e.getMessage(), null, null, new Date(), actualCollection, null, null);
+			return new SolrHealthStatus(false, e.getMessage(), null, null, Instant.now(), actualCollection, null, null);
 		}
 	}
 
@@ -1027,6 +1027,6 @@ public CollectionCreationResult createCollection(
 		CollectionAdminRequest.createCollection(name, effectiveConfigSet, effectiveShards, effectiveRf)
 				.process(solrClient);
 
-		return new CollectionCreationResult(name, true, "Collection created successfully", new Date());
+		return new CollectionCreationResult(name, true, "Collection created successfully", Instant.now());
 	}
 }
diff --git a/src/main/java/org/apache/solr/mcp/server/collection/Dtos.java b/src/main/java/org/apache/solr/mcp/server/collection/Dtos.java
index 13a898ef..7a377991 100644
--- a/src/main/java/org/apache/solr/mcp/server/collection/Dtos.java
+++ b/src/main/java/org/apache/solr/mcp/server/collection/Dtos.java
@@ -19,7 +19,7 @@
 import com.fasterxml.jackson.annotation.JsonFormat;
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonInclude;
-import java.util.Date;
+import java.time.Instant;
 
 /**
  * Data Transfer Objects (DTOs) for the Apache Solr MCP Server.
@@ -104,7 +104,7 @@ record SolrMetrics(
 		HandlerStats handlerStats,
 
 		/** Timestamp when these metrics were collected, formatted as ISO 8601 */
-		@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'") Date timestamp) {
+		@JsonFormat(shape = JsonFormat.Shape.STRING) Instant timestamp) {
 }
 
 /**
@@ -464,7 +464,7 @@ record SolrHealthStatus(
 		Long totalDocuments,
 
 		/** Timestamp when this health check was performed, formatted as ISO 8601 */
-		@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'") Date lastChecked,
+		@JsonFormat(shape = JsonFormat.Shape.STRING) Instant lastChecked,
 
 		/** Name of the collection that was checked */
 		String collection,
@@ -497,5 +497,5 @@ record CollectionCreationResult(
 		String message,
 
 		/** Timestamp when the collection was created, formatted as ISO 8601 */
-		@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'") Date createdAt) {
+		@JsonFormat(shape = JsonFormat.Shape.STRING) Instant createdAt) {
 }
diff --git a/src/test/java/org/apache/solr/mcp/server/collection/CollectionServiceIntegrationTest.java b/src/test/java/org/apache/solr/mcp/server/collection/CollectionServiceIntegrationTest.java
index 788b9527..3c3a2e1d 100644
--- a/src/test/java/org/apache/solr/mcp/server/collection/CollectionServiceIntegrationTest.java
+++ b/src/test/java/org/apache/solr/mcp/server/collection/CollectionServiceIntegrationTest.java
@@ -173,7 +173,7 @@ void testCheckHealth_healthy() {
 		assertEquals((long) DOC_COUNT, status.totalDocuments(), "Health check should report indexed document count");
 
 		assertNotNull(status.lastChecked());
-		assertTrue(System.currentTimeMillis() - status.lastChecked().getTime() < 5000);
+		assertTrue(java.time.Duration.between(status.lastChecked(), java.time.Instant.now()).toMillis() < 5000);
 	}
 
 	@Test