fix(tool): handle non-existing tool callbacks gracefully

- Add error handling to SpringBeanToolCallbackResolver to return null
  instead of throwing exceptions when resolving non-existing tools.
  This make is consitent with other tool resolver implementations
  and centralize the error handling in the tool calling manager.
- Add test to verify that the ToolCallbackResolver correctly
  returns null for non-existing tools.

Related to #2667

Signed-off-by: Christian Tzolov <[email protected]>

Author: tzolov

auto-configurations/models/tool/spring-ai-autoconfigure-model-tool/src/test/java/org/springframework/ai/model/tool/autoconfigure/ToolCallingAutoConfigurationTests.java

@@ -99,6 +99,18 @@ void resolveMultipleFunctionAndToolCallbacks() {
 			});
 	}
 
+	@Test
+	void resolveMissingToolCallbacks() {
+		new ApplicationContextRunner().withConfiguration(AutoConfigurations.of(ToolCallingAutoConfiguration.class))
+			.withUserConfiguration(Config.class)
+			.run(context -> {
+				var toolCallbackResolver = context.getBean(ToolCallbackResolver.class);
+				assertThat(toolCallbackResolver).isInstanceOf(DelegatingToolCallbackResolver.class);
+
+				assertThat(toolCallbackResolver.resolve("NonExisting")).isNull();
+			});
+	}
+
 	static class WeatherService {
 
 		@Tool(description = "Get the weather in location. Return temperature in 36°F or 36°C format.")

spring-ai-model/src/main/java/org/springframework/ai/tool/resolution/SpringBeanToolCallbackResolver.java

@@ -88,18 +88,24 @@ public ToolCallback resolve(String toolName) {
 			return resolvedToolCallback;
 		}
 
-		ResolvableType toolType = TypeResolverHelper.resolveBeanType(this.applicationContext, toolName);
-		ResolvableType toolInputType = (ResolvableType.forType(Supplier.class).isAssignableFrom(toolType))
-				? ResolvableType.forType(Void.class) : TypeResolverHelper.getFunctionArgumentType(toolType, 0);
+		try {
+			ResolvableType toolType = TypeResolverHelper.resolveBeanType(this.applicationContext, toolName);
+			ResolvableType toolInputType = (ResolvableType.forType(Supplier.class).isAssignableFrom(toolType))
+					? ResolvableType.forType(Void.class) : TypeResolverHelper.getFunctionArgumentType(toolType, 0);
 
-		String toolDescription = resolveToolDescription(toolName, toolInputType.toClass());
-		Object bean = this.applicationContext.getBean(toolName);
+			String toolDescription = resolveToolDescription(toolName, toolInputType.toClass());
+			Object bean = this.applicationContext.getBean(toolName);
 
-		resolvedToolCallback = buildToolCallback(toolName, toolType, toolInputType, toolDescription, bean);
+			resolvedToolCallback = buildToolCallback(toolName, toolType, toolInputType, toolDescription, bean);
 
-		toolCallbacksCache.put(toolName, resolvedToolCallback);
+			toolCallbacksCache.put(toolName, resolvedToolCallback);
 
-		return resolvedToolCallback;
+			return resolvedToolCallback;
+		}
+		catch (Exception e) {
+			logger.debug("ToolCallback resolution failed from Spring application context", e);
+			return null;
+		}
 	}
 
 	public SchemaType getSchemaType() {