feat(mcp): add output schema toggle config (#24308)

* feat(mcp): add output schema toggle config

* Update changelog/unreleased/pr-24308.toml

Co-authored-by: Dennis Oelkers <[email protected]>

Author: monrax

changelog/unreleased/pr-24308.toml

@@ -0,0 +1,5 @@
+type = "added" # One of: a(dded), c(hanged), d(eprecated), r(emoved), f(ixed), s(ecurity)
+message = "Add option in MCP config for disabling schema output in responses."
+
+issues = ["23980"]
+pulls = ["24308"]

graylog2-server/src/main/java/org/graylog/mcp/config/McpConfiguration.java

@@ -24,13 +24,22 @@
 @JsonAutoDetect
 @AutoValue
 public abstract class McpConfiguration {
-    public static final McpConfiguration DEFAULT_VALUES = create(false);
+    public static final McpConfiguration DEFAULT_VALUES = create(
+            false,
+            false
+    );
 
     @JsonProperty("enable_remote_access")
     public abstract boolean enableRemoteAccess();
 
+    @JsonProperty("enable_output_schema")
+    public abstract boolean enableOutputSchema();
+
     @JsonCreator
-    public static McpConfiguration create(@JsonProperty("enable_remote_access") boolean enableRemoteAccess) {
-        return new AutoValue_McpConfiguration(enableRemoteAccess);
+    public static McpConfiguration create(
+            @JsonProperty("enable_remote_access") boolean enableRemoteAccess,
+            @JsonProperty("enable_output_schema") boolean enableOutputSchema
+    ) {
+        return new AutoValue_McpConfiguration(enableRemoteAccess, enableOutputSchema);
     }
 }

graylog2-server/src/main/java/org/graylog/mcp/server/McpService.java

@@ -164,7 +164,9 @@ public Optional<McpSchema.Result> handle(PermissionHelper permissionHelper, McpS
                             .title(tool.title())
                             .description(tool.description());
                     tool.inputSchema().ifPresent(builder::inputSchema);
-                    tool.outputSchema().ifPresent(builder::outputSchema);
+                    if (tool.isOutputSchemaEnabled()) {
+                        tool.outputSchema().ifPresent(builder::outputSchema);
+                    }
                     return builder.build();
                 }).toList();
                 auditEventSender.success(auditActor, AuditEventType.create(MCP_TOOL_LIST), auditContext);

graylog2-server/src/main/java/org/graylog/mcp/server/Tool.java

@@ -21,7 +21,11 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.github.victools.jsonschema.generator.SchemaGenerator;
 import io.modelcontextprotocol.spec.McpSchema;
+import jakarta.inject.Inject;
+import org.graylog.mcp.config.McpConfiguration;
 import org.graylog.mcp.tools.PermissionHelper;
+import org.graylog2.plugin.cluster.ClusterConfigService;
+import org.graylog2.web.customization.CustomizationConfig;
 
 import java.util.Map;
 import java.util.Optional;
@@ -33,29 +37,56 @@
  * @param <O> Output type
  */
 public abstract class Tool<P, O> {
-
     private final ObjectMapper objectMapper;
+    private final ClusterConfigService clusterConfigService;
+
     private final TypeReference<P> parameterType;
     private final String name;
     private final String title;
     private final String description;
     private final McpSchema.JsonSchema inputSchema;
     private final Map<String, Object> outputSchema;
 
+    @Deprecated
     protected Tool(
             ObjectMapper objectMapper,
             SchemaGeneratorProvider schemaGeneratorProvider,
             TypeReference<P> parameterType,
             TypeReference<O> outputType,
             String name,
             String title,
-            String description) {
-        this.objectMapper = objectMapper;
+            String description
+    ) {
+        this(
+                parameterType,
+                outputType,
+                name,
+                title,
+                description,
+                objectMapper,
+                null,
+                schemaGeneratorProvider
+        );
+    }
+
+    protected Tool(
+            TypeReference<P> parameterType,
+            TypeReference<O> outputType,
+            String name,
+            String title,
+            String description,
+            ObjectMapper objectMapper,
+            ClusterConfigService clusterConfigService,
+            SchemaGeneratorProvider schemaGeneratorProvider
+    ) {
         this.parameterType = parameterType;
         this.name = name;
         this.title = title;
         this.description = description;
 
+        this.objectMapper = objectMapper;
+        this.clusterConfigService = clusterConfigService;
+
         // Get the schema generator with all contributed modules
         SchemaGenerator generator = schemaGeneratorProvider.get();
 
@@ -74,6 +105,11 @@ protected Tool(
         }
     }
 
+    protected boolean isOutputSchemaEnabled() {
+        return clusterConfigService != null && clusterConfigService.getOrDefault(McpConfiguration.class, McpConfiguration.DEFAULT_VALUES)
+                .enableOutputSchema();
+    }
+
     protected ObjectMapper getObjectMapper() {
         return objectMapper;
     }

graylog2-server/src/main/java/org/graylog/mcp/tools/AggregateMessagesTool.java

@@ -35,6 +35,7 @@
 import org.graylog.plugins.views.search.rest.scriptingapi.request.Grouping;
 import org.graylog.plugins.views.search.rest.scriptingapi.request.Metric;
 import org.graylog.plugins.views.search.rest.scriptingapi.response.TabularResponse;
+import org.graylog2.plugin.cluster.ClusterConfigService;
 import org.graylog2.plugin.indexer.searches.timeranges.RelativeRange;
 import org.graylog2.web.customization.CustomizationConfig;
 import org.slf4j.Logger;
@@ -52,12 +53,12 @@ public class AggregateMessagesTool extends Tool<AggregateMessagesTool.Parameters
     private final ScriptingApiService scriptingApiService;
 
     @Inject
-    public AggregateMessagesTool(ObjectMapper objectMapper,
-                                 CustomizationConfig customizationConfig,
-                                 SchemaGeneratorProvider schemaGeneratorProvider,
-                                 ScriptingApiService scriptingApiService) {
-        super(objectMapper,
-                schemaGeneratorProvider,
+    public AggregateMessagesTool(ScriptingApiService scriptingApiService,
+                                 final CustomizationConfig customizationConfig,
+                                 final ObjectMapper objectMapper,
+                                 final ClusterConfigService clusterConfigService,
+                                 final SchemaGeneratorProvider schemaGeneratorProvider) {
+        super(
                 new TypeReference<>() {},
                 new TypeReference<>() {},
                 NAME,
@@ -70,7 +71,11 @@ You can scope the search to streams (by passing their IDs) or stream categories,
                         You need to provide at least one grouping, a field name and limit, as well as one metric to calculate for the group by buckets.
                         For example, to count the top 10 number of messages per source, you can send {"groupings": [{"field":"source", "limit": 10}], "metrics": {"function":"count"}}
                         The query string supports Lucene query language, but be careful about leading wildcards, %1$s might not have them enabled.
-                        """.formatted(customizationConfig.productName()));
+                        """.formatted(customizationConfig.productName()),
+                objectMapper,
+                clusterConfigService,
+                schemaGeneratorProvider
+                );
         this.scriptingApiService = scriptingApiService;
     }
 

graylog2-server/src/main/java/org/graylog/mcp/tools/CurrentTimeTool.java

@@ -22,6 +22,7 @@
 import org.graylog.mcp.server.SchemaGeneratorProvider;
 import org.graylog.mcp.server.Tool;
 import org.graylog2.plugin.Tools;
+import org.graylog2.plugin.cluster.ClusterConfigService;
 import org.graylog2.web.customization.CustomizationConfig;
 import org.joda.time.DateTime;
 import org.joda.time.DateTimeZone;
@@ -40,16 +41,23 @@ public class CurrentTimeTool extends Tool<CurrentTimeTool.Parameters, String> {
     public static String NAME = "get_current_time";
 
     @Inject
-    public CurrentTimeTool(ObjectMapper objectMapper,
-                           CustomizationConfig customizationConfig,
-                           SchemaGeneratorProvider schemaGeneratorProvider) {
-        super(objectMapper,
-                schemaGeneratorProvider,
+    public CurrentTimeTool(final CustomizationConfig customizationConfig,
+                           final ObjectMapper objectMapper,
+                           final ClusterConfigService clusterConfigService,
+                           final SchemaGeneratorProvider schemaGeneratorProvider) {
+        super(
                 new TypeReference<>() {},
                 new TypeReference<>() {},
                 NAME,
                 "Get current time",
-                f("Return the current time from the %s server in ISO‑8601 UTC format.", customizationConfig.productName()));
+                f(
+                        "Return the current time from the %s server in ISO‑8601 UTC format.",
+                        customizationConfig.productName()
+                ),
+                objectMapper,
+                clusterConfigService,
+                schemaGeneratorProvider
+        );
     }
 
     @Override

graylog2-server/src/main/java/org/graylog/mcp/tools/ListFieldsTool.java

@@ -25,10 +25,11 @@
 import com.google.auto.value.AutoValue;
 import jakarta.annotation.Nullable;
 import jakarta.inject.Inject;
-import org.graylog.mcp.server.Tool;
 import org.graylog.mcp.server.SchemaGeneratorProvider;
+import org.graylog.mcp.server.Tool;
 import org.graylog.plugins.views.search.rest.MappedFieldTypeDTO;
 import org.graylog2.indexer.fieldtypes.MappedFieldTypesService;
+import org.graylog2.plugin.cluster.ClusterConfigService;
 import org.graylog2.plugin.indexer.searches.timeranges.RelativeRange;
 
 import java.util.Set;
@@ -40,22 +41,28 @@ public class ListFieldsTool extends Tool<ListFieldsTool.Parameters, ListFieldsTo
     private final MappedFieldTypesService mappedFieldTypesService;
 
     @Inject
-    protected ListFieldsTool(final ObjectMapper objectMapper,
-            SchemaGeneratorProvider schemaGeneratorProvider, MappedFieldTypesService mappedFieldTypesService) {
-        super(objectMapper,
-                schemaGeneratorProvider,
-              new TypeReference<>() {},
-              new TypeReference<>() {},
-              NAME,
+    protected ListFieldsTool(MappedFieldTypesService mappedFieldTypesService,
+                             final ObjectMapper objectMapper,
+                             final ClusterConfigService clusterConfigService,
+                             final SchemaGeneratorProvider schemaGeneratorProvider) {
+        super(
+                new TypeReference<>() {},
+                new TypeReference<>() {},
+                NAME,
               "List available fields",
-              """
-                      Retrieve the available field names and metadata about them, for example their datatype and capabilities.
-                      Field names must be used to properly create search queries and request specific fields from tools like
-                      search_messages and aggregate_messages.
-                      Fields can have different meanings in different streams (and also per source), so that needs to be taken into account.
-                      This tool can be scoped to streams to cut down on the noise.
-                      Fields can have various properties, such as "enumerable" which means you can aggregate on them, they can be "numeric",
-                      making them suitable to use in aggregation metrics, or "full-text-search", which means their content is tokenized""");
+                """
+                Retrieve the available field names and metadata about them, for example their datatype and capabilities.
+                Field names must be used to properly create search queries and request specific fields from tools like
+                search_messages and aggregate_messages.
+                Fields can have different meanings in different streams (and also per source), so that needs to be taken into account.
+                This tool can be scoped to streams to cut down on the noise.
+                Fields can have various properties, such as "enumerable" which means you can aggregate on them, they can be "numeric",
+                making them suitable to use in aggregation metrics, or "full-text-search", which means their content is tokenized
+                """,
+                objectMapper,
+                clusterConfigService,
+                schemaGeneratorProvider
+        );
         this.mappedFieldTypesService = mappedFieldTypesService;
     }
 

graylog2-server/src/main/java/org/graylog/mcp/tools/ListIndexSetsTool.java

@@ -26,6 +26,7 @@
 import org.graylog2.indexer.rotation.strategies.SizeBasedRotationStrategyConfig;
 import org.graylog2.indexer.rotation.strategies.TimeBasedRotationStrategyConfig;
 import org.graylog2.indexer.rotation.strategies.TimeBasedSizeOptimizingStrategyConfig;
+import org.graylog2.plugin.cluster.ClusterConfigService;
 import org.graylog2.plugin.indexer.rotation.RotationStrategyConfig;
 import org.graylog2.rest.resources.system.indexer.responses.IndexSetResponse;
 import org.graylog2.shared.security.RestPermissions;
@@ -40,16 +41,16 @@
 public class ListIndexSetsTool extends Tool<ListIndexSetsTool.Parameters, String> {
     public static String NAME = "list_index_sets";
 
-    private final String productName;
     private final IndexSetService indexSetService;
+    private final CustomizationConfig customizationConfig;
 
     @Inject
-    public ListIndexSetsTool(ObjectMapper objectMapper,
-                             SchemaGeneratorProvider schemaGeneratorProvider,
-                             CustomizationConfig customizationConfig,
-                             IndexSetService indexSetService) {
-        super(objectMapper,
-                schemaGeneratorProvider,
+    public ListIndexSetsTool(IndexSetService indexSetService,
+                             final CustomizationConfig customizationConfig,
+                             final ObjectMapper objectMapper,
+                             final ClusterConfigService clusterConfigService,
+                             final SchemaGeneratorProvider schemaGeneratorProvider) {
+        super(
                 new TypeReference<>() {},
                 new TypeReference<>() {},
                 NAME,
@@ -59,9 +60,13 @@ public ListIndexSetsTool(ObjectMapper objectMapper,
                         retention settings (how long data is kept), index prefix patterns, and current state. Use this to understand data lifecycle management,
                         troubleshoot retention issues, or plan storage capacity. Essential for understanding how your log data is organized and managed over time.
                         No parameters required. Returns index set details.
-                        """.formatted(customizationConfig.productName()));
-        this.productName = customizationConfig.productName();
+                        """.formatted(customizationConfig.productName()),
+                objectMapper,
+                clusterConfigService,
+                schemaGeneratorProvider
+        );
         this.indexSetService = indexSetService;
+        this.customizationConfig = customizationConfig;
     }
 
     @Override
@@ -70,7 +75,7 @@ public String apply(PermissionHelper permissionHelper, ListIndexSetsTool.Paramet
 
         final var indexSets = indexSetService.findAll();
         if (indexSets.isEmpty()) {
-            return f("No index sets found in the %s server.", productName);
+            return f("No index sets found in the %s server.", customizationConfig.productName());
         }
 
         final var defaultIndexSet = indexSetService.getDefault();
@@ -83,7 +88,7 @@ public String apply(PermissionHelper permissionHelper, ListIndexSetsTool.Paramet
         final var sw = new StringWriter();
         final var pw = new PrintWriter(sw);
 
-        pw.println(f("%s Index Sets:", productName));
+        pw.println(f("%s Index Sets:", customizationConfig.productName()));
         indexSetConfigStream.forEach(pw::println);
 
         return sw.toString();

graylog2-server/src/main/java/org/graylog/mcp/tools/ListIndicesTool.java

@@ -28,6 +28,7 @@
 import org.graylog2.indexer.indices.Indices;
 import org.graylog2.indexer.indices.stats.IndexStatistics;
 import org.graylog2.indexer.indices.util.NumberBasedIndexNameComparator;
+import org.graylog2.plugin.cluster.ClusterConfigService;
 import org.graylog2.rest.models.system.indexer.responses.AllIndices;
 import org.graylog2.rest.models.system.indexer.responses.ClosedIndices;
 import org.graylog2.rest.models.system.indexer.responses.IndexInfo;
@@ -56,14 +57,14 @@ public class ListIndicesTool extends Tool<ListIndicesTool.Parameters, String> {
     private final IndexSetRegistry indexSetRegistry;
 
     @Inject
-    public ListIndicesTool(ObjectMapper objectMapper,
-                           SchemaGeneratorProvider schemaGeneratorProvider,
-                           Indices indices,
+    public ListIndicesTool(Indices indices,
                            NodeInfoCache nodeInfoCache,
                            IndexSetRegistry indexSetRegistry,
-                           CustomizationConfig customizationConfig) {
-        super(objectMapper,
-                schemaGeneratorProvider,
+                           final CustomizationConfig customizationConfig,
+                           final ObjectMapper objectMapper,
+                           final ClusterConfigService clusterConfigService,
+                           final SchemaGeneratorProvider schemaGeneratorProvider) {
+        super(
                 new TypeReference<>() {},
                 new TypeReference<>() {},
                 NAME,
@@ -72,7 +73,13 @@ public ListIndicesTool(ObjectMapper objectMapper,
                         List all %s indices from the cluster. Returns comprehensive index information including status (open/closed),
                         document counts, storage size, and health metrics. Use this to understand data distribution, identify problematic indices,
                         or before performing queries to understand available data sources. No parameters required.
-                        """, customizationConfig.productName()));
+                        """,
+                        customizationConfig.productName()
+                ),
+                objectMapper,
+                clusterConfigService,
+                schemaGeneratorProvider
+        );
         this.indices = indices;
         this.nodeInfoCache = nodeInfoCache;
         this.indexSetRegistry = indexSetRegistry;