Add support filter tool/resources

[He-Pin]

Motivation:
We need to filter the tool and resources. When the client requests a tool list or a resource list, we need to filter out the tools/resources which is not visible to some users.

It would be nice to set filter* to Mcp*Servedr

[jahlbornG]

yes, we have this need as well.

[jahlbornG]

i took a crack at adding support for filtering tool lists to the project (note that this diff also includes the context patch from #226 ):

diff --git a/mcp/src/main/java/io/modelcontextprotocol/server/McpAsyncServer.java b/mcp/src/main/java/io/modelcontextprotocol/server/McpAsyncServer.java
index ef1e512..eb9a824 100644
--- a/mcp/src/main/java/io/modelcontextprotocol/server/McpAsyncServer.java
+++ b/mcp/src/main/java/io/modelcontextprotocol/server/McpAsyncServer.java
@@ -14,9 +14,11 @@ import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.function.BiFunction;
+import java.util.function.Predicate;
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import io.modelcontextprotocol.server.McpServerFeatures.AsyncToolSpecification;
 import io.modelcontextprotocol.spec.*;
 import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
 import io.modelcontextprotocol.spec.McpSchema.LoggingLevel;
@@ -25,6 +27,7 @@ import io.modelcontextprotocol.spec.McpSchema.ResourceTemplate;
 import io.modelcontextprotocol.spec.McpSchema.SetLevelRequest;
 import io.modelcontextprotocol.spec.McpSchema.Tool;
 import io.modelcontextprotocol.util.DeafaultMcpUriTemplateManagerFactory;
+import io.modelcontextprotocol.util.McpAsyncToolFilterFactory;
 import io.modelcontextprotocol.util.McpUriTemplateManagerFactory;
 import io.modelcontextprotocol.util.Utils;
 import org.slf4j.Logger;
@@ -106,6 +109,8 @@ public class McpAsyncServer {
 
 	private McpUriTemplateManagerFactory uriTemplateManagerFactory = new DeafaultMcpUriTemplateManagerFactory();
 
+	private final McpAsyncToolFilterFactory toolFilterFactory;
+
 	/**
 	 * Create a new McpAsyncServer with the given transport provider and capabilities.
 	 * @param mcpTransportProvider The transport layer implementation for MCP
@@ -115,7 +120,7 @@ public class McpAsyncServer {
 	 */
 	McpAsyncServer(McpServerTransportProvider mcpTransportProvider, ObjectMapper objectMapper,
 			McpServerFeatures.Async features, Duration requestTimeout,
-			McpUriTemplateManagerFactory uriTemplateManagerFactory) {
+			McpUriTemplateManagerFactory uriTemplateManagerFactory, McpAsyncToolFilterFactory toolFilterFactory) {
 		this.mcpTransportProvider = mcpTransportProvider;
 		this.objectMapper = objectMapper;
 		this.serverInfo = features.serverInfo();
@@ -127,6 +132,7 @@ public class McpAsyncServer {
 		this.prompts.putAll(features.prompts());
 		this.completions.putAll(features.completions());
 		this.uriTemplateManagerFactory = uriTemplateManagerFactory;
+		this.toolFilterFactory = toolFilterFactory;
 
 		Map<String, McpServerSession.RequestHandler<?>> requestHandlers = new HashMap<>();
 
@@ -341,7 +347,14 @@ public class McpAsyncServer {
 
 	private McpServerSession.RequestHandler<McpSchema.ListToolsResult> toolsListRequestHandler() {
 		return (exchange, params, context) -> {
-			List<Tool> tools = this.tools.stream().map(McpServerFeatures.AsyncToolSpecification::tool).toList();
+
+			Predicate<AsyncToolSpecification> toolsFilter = toolFilterFactory != null
+					? toolFilterFactory.createFilter(exchange, params, context) : t -> true;
+
+			List<Tool> tools = this.tools.stream()
+				.filter(toolsFilter)
+				.map(McpServerFeatures.AsyncToolSpecification::tool)
+				.toList();
 
 			return Mono.just(new McpSchema.ListToolsResult(tools, null));
 		};
diff --git a/mcp/src/main/java/io/modelcontextprotocol/server/McpServer.java b/mcp/src/main/java/io/modelcontextprotocol/server/McpServer.java
index 083beb6..3c7c00b 100644
--- a/mcp/src/main/java/io/modelcontextprotocol/server/McpServer.java
+++ b/mcp/src/main/java/io/modelcontextprotocol/server/McpServer.java
@@ -20,6 +20,8 @@ import io.modelcontextprotocol.spec.McpSchema.ResourceTemplate;
 import io.modelcontextprotocol.spec.McpServerTransportProvider;
 import io.modelcontextprotocol.util.Assert;
 import io.modelcontextprotocol.util.DeafaultMcpUriTemplateManagerFactory;
+import io.modelcontextprotocol.util.McpAsyncToolFilterFactory;
+import io.modelcontextprotocol.util.McpSyncToolFilterFactory;
 import io.modelcontextprotocol.util.McpUriTemplateManagerFactory;
 import reactor.core.publisher.Mono;
 
@@ -203,6 +205,8 @@ public interface McpServer {
 
 		private Duration requestTimeout = Duration.ofSeconds(10); // Default timeout
 
+		private McpAsyncToolFilterFactory toolFilterFactory;
+
 		private AsyncSpecification(McpServerTransportProvider transportProvider) {
 			Assert.notNull(transportProvider, "Transport provider must not be null");
 			this.transportProvider = transportProvider;
@@ -624,6 +628,18 @@ public interface McpServer {
 			return this;
 		}
 
+		/**
+		 * Sets the tool filter factory that will be used to create filters for tool
+		 * lists.
+		 * @param toolFilterFactory The factory to use. Must not be null.
+		 * @return This builder instance for method chaining.
+		 */
+		public AsyncSpecification toolFilterFactory(McpAsyncToolFilterFactory toolFilterFactory) {
+			Assert.notNull(toolFilterFactory, "Tool filter factory must not be null");
+			this.toolFilterFactory = toolFilterFactory;
+			return this;
+		}
+
 		/**
 		 * Builds an asynchronous MCP server that provides non-blocking operations.
 		 * @return A new instance of {@link McpAsyncServer} configured with this builder's
@@ -635,7 +651,7 @@ public interface McpServer {
 					this.instructions);
 			var mapper = this.objectMapper != null ? this.objectMapper : new ObjectMapper();
 			return new McpAsyncServer(this.transportProvider, mapper, features, this.requestTimeout,
-					this.uriTemplateManagerFactory);
+					this.uriTemplateManagerFactory, this.toolFilterFactory);
 		}
 
 	}
@@ -695,6 +711,8 @@ public interface McpServer {
 
 		private Duration requestTimeout = Duration.ofSeconds(10); // Default timeout
 
+		private McpSyncToolFilterFactory toolFilterFactory;
+
 		private SyncSpecification(McpServerTransportProvider transportProvider) {
 			Assert.notNull(transportProvider, "Transport provider must not be null");
 			this.transportProvider = transportProvider;
@@ -1116,6 +1134,18 @@ public interface McpServer {
 			return this;
 		}
 
+		/**
+		 * Sets the tool filter factory that will be used to create filters for tool
+		 * lists.
+		 * @param toolFilterFactory The factory to use. Must not be null.
+		 * @return This builder instance for method chaining.
+		 */
+		public SyncSpecification toolFilterFactory(McpSyncToolFilterFactory toolFilterFactory) {
+			Assert.notNull(toolFilterFactory, "Tool filter factory must not be null");
+			this.toolFilterFactory = toolFilterFactory;
+			return this;
+		}
+
 		/**
 		 * Builds a synchronous MCP server that provides blocking operations.
 		 * @return A new instance of {@link McpSyncServer} configured with this builder's
@@ -1127,8 +1157,10 @@ public interface McpServer {
 					this.rootsChangeHandlers, this.instructions);
 			McpServerFeatures.Async asyncFeatures = McpServerFeatures.Async.fromSync(syncFeatures);
 			var mapper = this.objectMapper != null ? this.objectMapper : new ObjectMapper();
+			var asyncToolFilterFactory = this.toolFilterFactory != null
+					? McpAsyncToolFilterFactory.fromSync(this.toolFilterFactory) : null;
 			var asyncServer = new McpAsyncServer(this.transportProvider, mapper, asyncFeatures, this.requestTimeout,
-					this.uriTemplateManagerFactory);
+					this.uriTemplateManagerFactory, asyncToolFilterFactory);
 
 			return new McpSyncServer(asyncServer);
 		}
diff --git a/mcp/src/main/java/io/modelcontextprotocol/server/McpServerFeatures.java b/mcp/src/main/java/io/modelcontextprotocol/server/McpServerFeatures.java
index 122857a..ce4b97c 100644
--- a/mcp/src/main/java/io/modelcontextprotocol/server/McpServerFeatures.java
+++ b/mcp/src/main/java/io/modelcontextprotocol/server/McpServerFeatures.java
@@ -238,7 +238,13 @@ public class McpServerFeatures {
 	 * connected client. The second arguments is a map of tool arguments.
 	 */
 	public record AsyncToolSpecification(McpSchema.Tool tool,
+			BiFunction<McpAsyncServerExchange, RequestWithContext<McpSchema.CallToolRequest>, Mono<McpSchema.CallToolResult>> call,
+			SyncToolSpecification syncTool) {
+
+		public AsyncToolSpecification(McpSchema.Tool tool,
 				BiFunction<McpAsyncServerExchange, RequestWithContext<McpSchema.CallToolRequest>, Mono<McpSchema.CallToolResult>> call) {
+			this(tool, call, null);
+		}
 
 		static AsyncToolSpecification fromSync(SyncToolSpecification tool) {
 			// FIXME: This is temporary, proper validation should be implemented
@@ -248,7 +254,8 @@ public class McpServerFeatures {
 			return new AsyncToolSpecification(tool.tool(),
 					(exchange, reqWithContext) -> Mono
 						.fromCallable(() -> tool.call().apply(new McpSyncServerExchange(exchange), reqWithContext))
-						.subscribeOn(Schedulers.boundedElastic()));
+						.subscribeOn(Schedulers.boundedElastic()),
+					tool);
 		}
 	}
 
diff --git a/mcp/src/main/java/io/modelcontextprotocol/util/McpAsyncToolFilterFactory.java b/mcp/src/main/java/io/modelcontextprotocol/util/McpAsyncToolFilterFactory.java
new file mode 100644
index 0000000..831ca1a
--- /dev/null
+++ b/mcp/src/main/java/io/modelcontextprotocol/util/McpAsyncToolFilterFactory.java
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+package io.modelcontextprotocol.util;
+
+import java.util.function.Predicate;
+
+import io.modelcontextprotocol.server.McpAsyncServerExchange;
+import io.modelcontextprotocol.server.McpServerFeatures.AsyncToolSpecification;
+import io.modelcontextprotocol.server.McpServerFeatures.SyncToolSpecification;
+import io.modelcontextprotocol.server.McpSyncServerExchange;
+import io.modelcontextprotocol.spec.McpContext;
+
+public interface McpAsyncToolFilterFactory {
+
+	public Predicate<AsyncToolSpecification> createFilter(McpAsyncServerExchange exchange, Object params,
+			McpContext mcpContext);
+
+	public static McpAsyncToolFilterFactory fromSync(McpSyncToolFilterFactory syncToolFilterFactory) {
+		return (exchange, params, mcpContext) -> {
+			Predicate<SyncToolSpecification> syncFilter = syncToolFilterFactory
+				.createFilter(new McpSyncServerExchange(exchange), params, mcpContext);
+			return asyncToolSpec -> syncFilter.test(asyncToolSpec.syncTool());
+		};
+	}
+
+}
diff --git a/mcp/src/main/java/io/modelcontextprotocol/util/McpSyncToolFilterFactory.java b/mcp/src/main/java/io/modelcontextprotocol/util/McpSyncToolFilterFactory.java
new file mode 100644
index 0000000..b28c0a0
--- /dev/null
+++ b/mcp/src/main/java/io/modelcontextprotocol/util/McpSyncToolFilterFactory.java
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+package io.modelcontextprotocol.util;
+
+import java.util.function.Predicate;
+
+import io.modelcontextprotocol.server.McpServerFeatures.SyncToolSpecification;
+import io.modelcontextprotocol.server.McpSyncServerExchange;
+import io.modelcontextprotocol.spec.McpContext;
+
+public interface McpSyncToolFilterFactory {
+
+	public Predicate<SyncToolSpecification> createFilter(McpSyncServerExchange exchange, Object params,
+			McpContext mcpContext);
+
+}