Simplify tool specification sanitization logic and improve test assertions for tool order and properties.

Author: amaan75

mcp-core/src/main/java/io/modelcontextprotocol/server/McpAsyncServer.java

@@ -409,11 +409,9 @@ public Mono<Void> addTools(List<McpServerFeatures.AsyncToolSpecification> toolSp
 
 	private List<McpServerFeatures.AsyncToolSpecification> sanitizeToolSpecifications(
 			List<McpServerFeatures.AsyncToolSpecification> toolSpecifications) {
-		List<McpServerFeatures.AsyncToolSpecification> copiedToolSpecifications = new ArrayList<>(toolSpecifications);
 		LinkedHashMap<String, McpServerFeatures.AsyncToolSpecification> toolSpecificationsByName = new LinkedHashMap<>();
 
-		for (int i = copiedToolSpecifications.size() - 1; i >= 0; i--) {
-			var toolSpecification = copiedToolSpecifications.get(i);
+		for (var toolSpecification : toolSpecifications) {
 			if (toolSpecification == null) {
 				throw new IllegalArgumentException("Tool specification must not be null");
 			}
@@ -424,13 +422,10 @@ private List<McpServerFeatures.AsyncToolSpecification> sanitizeToolSpecification
 				throw new IllegalArgumentException("Tool call handler must not be null");
 			}
 			var wrappedToolSpecification = withStructuredOutputHandling(this.jsonSchemaValidator, toolSpecification);
-			toolSpecificationsByName.putIfAbsent(wrappedToolSpecification.tool().name(), wrappedToolSpecification);
+			toolSpecificationsByName.put(wrappedToolSpecification.tool().name(), wrappedToolSpecification);
 		}
 
-		List<McpServerFeatures.AsyncToolSpecification> sanitizedToolSpecifications = new ArrayList<>(
-				toolSpecificationsByName.values());
-		Collections.reverse(sanitizedToolSpecifications);
-		return sanitizedToolSpecifications;
+		return new ArrayList<>(toolSpecificationsByName.values());
 	}
 
 	private static class StructuredOutputCallToolHandler

mcp-core/src/main/java/io/modelcontextprotocol/server/McpStatelessAsyncServer.java

@@ -30,7 +30,6 @@
 
 import java.time.Duration;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
@@ -396,12 +395,9 @@ public Mono<Void> addTools(List<McpStatelessServerFeatures.AsyncToolSpecificatio
 
 	private List<McpStatelessServerFeatures.AsyncToolSpecification> sanitizeToolSpecifications(
 			List<McpStatelessServerFeatures.AsyncToolSpecification> toolSpecifications) {
-		List<McpStatelessServerFeatures.AsyncToolSpecification> copiedToolSpecifications = new ArrayList<>(
-				toolSpecifications);
 		LinkedHashMap<String, McpStatelessServerFeatures.AsyncToolSpecification> toolSpecificationsByName = new LinkedHashMap<>();
 
-		for (int i = copiedToolSpecifications.size() - 1; i >= 0; i--) {
-			var toolSpecification = copiedToolSpecifications.get(i);
+		for (var toolSpecification : toolSpecifications) {
 			if (toolSpecification == null) {
 				throw new IllegalArgumentException("Tool specification must not be null");
 			}
@@ -412,13 +408,10 @@ private List<McpStatelessServerFeatures.AsyncToolSpecification> sanitizeToolSpec
 				throw new IllegalArgumentException("Tool call handler must not be null");
 			}
 			var wrappedToolSpecification = withStructuredOutputHandling(this.jsonSchemaValidator, toolSpecification);
-			toolSpecificationsByName.putIfAbsent(wrappedToolSpecification.tool().name(), wrappedToolSpecification);
+			toolSpecificationsByName.put(wrappedToolSpecification.tool().name(), wrappedToolSpecification);
 		}
 
-		List<McpStatelessServerFeatures.AsyncToolSpecification> sanitizedToolSpecifications = new ArrayList<>(
-				toolSpecificationsByName.values());
-		Collections.reverse(sanitizedToolSpecifications);
-		return sanitizedToolSpecifications;
+		return new ArrayList<>(toolSpecificationsByName.values());
 	}
 
 	/**

mcp-test/src/main/java/io/modelcontextprotocol/server/AbstractMcpAsyncServerTests.java

@@ -275,8 +275,12 @@ void testAddToolsWithDuplicateInputKeepsLastOccurrence() {
 			.verifyComplete();
 
 		StepVerifier.create(mcpAsyncServer.listTools().collectList()).assertNext(tools -> {
-			assertThat(tools).extracting(McpSchema.Tool::name).containsExactly("middle-tool", "duplicate-tool");
-			assertThat(tools.get(1).title()).isEqualTo("Last tool");
+			assertThat(tools).extracting(McpSchema.Tool::name)
+				.containsExactlyInAnyOrder("middle-tool", "duplicate-tool");
+			assertThat(tools).filteredOn(tool -> tool.name().equals("duplicate-tool"))
+				.singleElement()
+				.extracting(McpSchema.Tool::title)
+				.isEqualTo("Last tool");
 		}).verifyComplete();
 
 		assertThatCode(() -> mcpAsyncServer.closeGracefully().block(Duration.ofSeconds(10))).doesNotThrowAnyException();

mcp-test/src/main/java/io/modelcontextprotocol/server/AbstractMcpSyncServerTests.java

@@ -264,8 +264,11 @@ void testAddToolsWithDuplicateInputKeepsLastOccurrence() {
 			.doesNotThrowAnyException();
 
 		assertThat(mcpSyncServer.listTools()).extracting(McpSchema.Tool::name)
-			.containsExactly("middle-tool", "duplicate-tool");
-		assertThat(mcpSyncServer.listTools().get(1).title()).isEqualTo("Last tool");
+			.containsExactlyInAnyOrder("middle-tool", "duplicate-tool");
+		assertThat(mcpSyncServer.listTools()).filteredOn(tool -> tool.name().equals("duplicate-tool"))
+			.singleElement()
+			.extracting(McpSchema.Tool::title)
+			.isEqualTo("Last tool");
 
 		assertThatCode(mcpSyncServer::closeGracefully).doesNotThrowAnyException();
 	}

mcp-test/src/test/java/io/modelcontextprotocol/server/HttpServletStatelessIntegrationTests.java

@@ -129,8 +129,12 @@ void testStatelessSyncBulkToolMutations(String clientType) {
 
 			await().atMost(Duration.ofSeconds(5)).untilAsserted(() -> {
 				List<Tool> tools = mcpClient.listTools().tools();
-				assertThat(tools).extracting(McpSchema.Tool::name).containsExactly("middle-tool", "duplicate-tool");
-				assertThat(tools.get(1).title()).isEqualTo("Last tool");
+				assertThat(tools).extracting(McpSchema.Tool::name)
+					.containsExactlyInAnyOrder("middle-tool", "duplicate-tool");
+				assertThat(tools).filteredOn(tool -> tool.name().equals("duplicate-tool"))
+					.singleElement()
+					.extracting(McpSchema.Tool::title)
+					.isEqualTo("Last tool");
 			});
 
 			mcpServer.addTools(List.of(syncToolSpecification("middle-tool", "Replacement tool"),