diff --git a/models/spring-ai-ollama/src/test/java/org/springframework/ai/ollama/aot/OllamaRuntimeHintsTests.java b/models/spring-ai-ollama/src/test/java/org/springframework/ai/ollama/aot/OllamaRuntimeHintsTests.java
index ae56cd033d3..26c5833c529 100644
--- a/models/spring-ai-ollama/src/test/java/org/springframework/ai/ollama/aot/OllamaRuntimeHintsTests.java
+++ b/models/spring-ai-ollama/src/test/java/org/springframework/ai/ollama/aot/OllamaRuntimeHintsTests.java
@@ -53,4 +53,101 @@ void registerHints() {
 		assertThat(registeredTypes.contains(TypeReference.of(OllamaOptions.class))).isTrue();
 	}
 
+	@Test
+	void registerHintsWithNullClassLoader() {
+		RuntimeHints runtimeHints = new RuntimeHints();
+		OllamaRuntimeHints ollamaRuntimeHints = new OllamaRuntimeHints();
+
+		// Should not throw exception with null ClassLoader
+		org.assertj.core.api.Assertions.assertThatCode(() -> ollamaRuntimeHints.registerHints(runtimeHints, null))
+			.doesNotThrowAnyException();
+	}
+
+	@Test
+	void ensureReflectionHintsAreRegistered() {
+		RuntimeHints runtimeHints = new RuntimeHints();
+		OllamaRuntimeHints ollamaRuntimeHints = new OllamaRuntimeHints();
+		ollamaRuntimeHints.registerHints(runtimeHints, null);
+
+		// Ensure reflection hints are properly registered
+		assertThat(runtimeHints.reflection().typeHints().spliterator().estimateSize()).isGreaterThan(0);
+	}
+
+	@Test
+	void verifyMultipleRegistrationCallsAreIdempotent() {
+		RuntimeHints runtimeHints = new RuntimeHints();
+		OllamaRuntimeHints ollamaRuntimeHints = new OllamaRuntimeHints();
+
+		// Register hints multiple times
+		ollamaRuntimeHints.registerHints(runtimeHints, null);
+		long firstCount = runtimeHints.reflection().typeHints().spliterator().estimateSize();
+
+		ollamaRuntimeHints.registerHints(runtimeHints, null);
+		long secondCount = runtimeHints.reflection().typeHints().spliterator().estimateSize();
+
+		// Should not register duplicate hints
+		assertThat(firstCount).isEqualTo(secondCount);
+	}
+
+	@Test
+	void verifyMainApiClassesRegistered() {
+		RuntimeHints runtimeHints = new RuntimeHints();
+		OllamaRuntimeHints ollamaRuntimeHints = new OllamaRuntimeHints();
+		ollamaRuntimeHints.registerHints(runtimeHints, null);
+
+		Set<TypeReference> registeredTypes = new HashSet<>();
+		runtimeHints.reflection().typeHints().forEach(typeHint -> registeredTypes.add(typeHint.getType()));
+
+		// Verify that the main classes we already know exist are registered
+		assertThat(registeredTypes.contains(TypeReference.of(OllamaApi.ChatRequest.class))).isTrue();
+		assertThat(registeredTypes.contains(TypeReference.of(OllamaApi.Message.class))).isTrue();
+		assertThat(registeredTypes.contains(TypeReference.of(OllamaOptions.class))).isTrue();
+	}
+
+	@Test
+	void verifyJsonAnnotatedClassesFromCorrectPackage() {
+		Set<TypeReference> jsonAnnotatedClasses = findJsonAnnotatedClassesInPackage("org.springframework.ai.ollama");
+
+		// Ensure we found some JSON annotated classes in the expected package
+		assertThat(jsonAnnotatedClasses.spliterator().estimateSize()).isGreaterThan(0);
+
+		// Verify all found classes are from the expected package
+		for (TypeReference classRef : jsonAnnotatedClasses) {
+			assertThat(classRef.getName()).startsWith("org.springframework.ai.ollama");
+		}
+	}
+
+	@Test
+	void verifyNoUnnecessaryHintsRegistered() {
+		RuntimeHints runtimeHints = new RuntimeHints();
+		OllamaRuntimeHints ollamaRuntimeHints = new OllamaRuntimeHints();
+		ollamaRuntimeHints.registerHints(runtimeHints, null);
+
+		Set<TypeReference> jsonAnnotatedClasses = findJsonAnnotatedClassesInPackage("org.springframework.ai.ollama");
+
+		Set<TypeReference> registeredTypes = new HashSet<>();
+		runtimeHints.reflection().typeHints().forEach(typeHint -> registeredTypes.add(typeHint.getType()));
+
+		// Ensure we don't register significantly more types than needed
+		// Allow for some additional utility types but prevent hint bloat
+		assertThat(registeredTypes.size()).isLessThanOrEqualTo(jsonAnnotatedClasses.size() + 15);
+	}
+
+	@Test
+	void verifyNestedClassHintsAreRegistered() {
+		RuntimeHints runtimeHints = new RuntimeHints();
+		OllamaRuntimeHints ollamaRuntimeHints = new OllamaRuntimeHints();
+		ollamaRuntimeHints.registerHints(runtimeHints, null);
+
+		Set<TypeReference> registeredTypes = new HashSet<>();
+		runtimeHints.reflection().typeHints().forEach(typeHint -> registeredTypes.add(typeHint.getType()));
+
+		// Verify nested classes that we know exist from the original test
+		assertThat(registeredTypes.contains(TypeReference.of(OllamaApi.ChatRequest.Tool.class))).isTrue();
+
+		// Count nested classes to ensure comprehensive registration
+		long nestedClassCount = registeredTypes.stream().filter(typeRef -> typeRef.getName().contains("$")).count();
+		assertThat(nestedClassCount).isGreaterThan(0);
+	}
+
 }