CAMEL-23476: camel-jbang-mcp: strip null fields from MCP JSON responses

dsl/camel-jbang/camel-jbang-mcp/src/main/resources/application.properties

@@ -32,3 +32,7 @@ quarkus.log.category."io.quarkiverse.mcp".level=INFO
 
 # Disable HTTP server - use STDIO transport only for CLI integration
 quarkus.http.host-enabled=false
+
+# Strip null fields from JSON responses to reduce LLM token consumption.
+# Applies to @Tool result records serialized via JsonTextContentEncoder.
+quarkus.jackson.serialization-inclusion=non-null

dsl/camel-jbang/camel-jbang-mcp/src/test/java/org/apache/camel/dsl/jbang/core/commands/mcp/McpJsonSerializationTest.java

@@ -0,0 +1,106 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.dsl.jbang.core.commands.mcp;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Properties;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Verifies the MCP server is configured to strip {@code null} fields from JSON responses. The Quarkus MCP framework
+ * serializes {@code @Tool} results through the default {@link ObjectMapper} produced by quarkus-jackson, which honors
+ * the {@code quarkus.jackson.serialization-inclusion} build-time property. CAMEL-23476.
+ */
+class McpJsonSerializationTest {
+
+    @Test
+    void applicationPropertiesEnforcesNonNullSerialization() throws IOException {
+        Properties props = new Properties();
+        try (InputStream in = getClass().getResourceAsStream("/application.properties")) {
+            assertThat(in).as("application.properties on classpath").isNotNull();
+            props.load(in);
+        }
+        assertThat(props.getProperty("quarkus.jackson.serialization-inclusion"))
+                .as("quarkus.jackson.serialization-inclusion must be 'non-null' to drop null fields from MCP responses")
+                .isEqualToIgnoringCase("non-null");
+    }
+
+    @Test
+    void componentInfoNullFieldsAreOmittedFromJson() throws Exception {
+        ObjectMapper mapper = newConfiguredObjectMapper();
+
+        CatalogTools.ComponentInfo info = new CatalogTools.ComponentInfo(
+                "timer", "Timer", null, null, false, null);
+
+        String json = mapper.writeValueAsString(info);
+
+        assertThat(json).contains("\"name\":\"timer\"");
+        assertThat(json).contains("\"title\":\"Timer\"");
+        assertThat(json).contains("\"deprecated\":false");
+        assertThat(json).doesNotContain("\"description\"");
+        assertThat(json).doesNotContain("\"label\"");
+        assertThat(json).doesNotContain("\"supportLevel\"");
+    }
+
+    @Test
+    void optionInfoNullGroupIsOmittedFromJson() throws Exception {
+        ObjectMapper mapper = newConfiguredObjectMapper();
+
+        // Matches the bug from CAMEL-23476: component options pass null for group while endpoint options populate it.
+        CatalogTools.OptionInfo opt = new CatalogTools.OptionInfo(
+                "bridgeErrorHandler", "Allows bridging the consumer", "boolean", false, "false", null);
+
+        String json = mapper.writeValueAsString(opt);
+
+        assertThat(json).contains("\"name\":\"bridgeErrorHandler\"");
+        assertThat(json).contains("\"required\":false");
+        assertThat(json).doesNotContain("\"group\"");
+    }
+
+    @Test
+    void componentDetailNullCollectionsAreOmittedFromJson() throws Exception {
+        ObjectMapper mapper = newConfiguredObjectMapper();
+
+        CatalogTools.ComponentDetailResult detail = new CatalogTools.ComponentDetailResult(
+                "timer", "Timer", null, null, false, null, null, null, null, null,
+                false, false, false, null, null);
+
+        String json = mapper.writeValueAsString(detail);
+
+        assertThat(json).contains("\"name\":\"timer\"");
+        assertThat(json).contains("\"async\":false");
+        assertThat(json).doesNotContain("\"description\"");
+        assertThat(json).doesNotContain("\"supportLevel\"");
+        assertThat(json).doesNotContain("\"groupId\"");
+        assertThat(json).doesNotContain("\"componentOptions\"");
+        assertThat(json).doesNotContain("\"endpointOptions\"");
+    }
+
+    private static ObjectMapper newConfiguredObjectMapper() {
+        ObjectMapper mapper = new ObjectMapper();
+        // Mirrors the configuration applied by Quarkus' ConfigurationCustomizer when
+        // quarkus.jackson.serialization-inclusion=non-null is set in application.properties.
+        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
+        return mapper;
+    }
+}