diff --git a/MIGRATION-2.0.md b/MIGRATION-2.0.md
index 273421189..261670768 100644
--- a/MIGRATION-2.0.md
+++ b/MIGRATION-2.0.md
@@ -77,6 +77,39 @@ The `Tool` record now models `inputSchema` (and `outputSchema`) as arbitrary JSO
 - Java code that used `Tool.inputSchema()` as a `JsonSchema` must switch to `Map<String, Object>` (or copy into your own schema wrapper).
 - `Tool.Builder.inputSchema(JsonSchema)` remains as a **deprecated** helper that maps the old record into a map; prefer `inputSchema(Map)` or `inputSchema(McpJsonMapper, String)`.
 
+### Required MCP spec fields are enforced at construction time; builders require them upfront
+
+The following records assert that their required fields are non-null at construction time. Passing `null` throws `IllegalArgumentException` immediately, rather than producing a structurally invalid object that fails later during serialization or protocol handling.
+
+| Record | Required (non-null) fields |
+|--------|---------------------------|
+| `JSONRPCResponse.JSONRPCError` | `code`, `message` |
+| `CallToolResult` | `content` |
+| `SamplingMessage` | `role`, `content` |
+| `CreateMessageRequest` | `messages`, `maxTokens` |
+| `ElicitRequest` | `message`, `requestedSchema` |
+| `ProgressNotification` | `progressToken`, `progress` |
+| `LoggingMessageNotification` | `level`, `data` |
+
+**Action:** Audit any code that constructs these records with potentially-null values and provide valid, non-null arguments.
+
+#### Builder API changes
+
+The builder factory methods for several records now require the mandatory fields as arguments, making it impossible to obtain a builder that is already missing required state. The old no-arg `builder()` factory and the public no-arg `Builder()` constructor are deprecated and will be removed in a future release.
+
+| Type | Old (deprecated) | New |
+|------|-----------------|-----|
+| `CreateMessageRequest` | `CreateMessageRequest.builder().messages(m).maxTokens(n)` | `CreateMessageRequest.builder(m, n)` |
+| `ElicitRequest` | `ElicitRequest.builder().message(m).requestedSchema(s)` | `ElicitRequest.builder(m, s)` |
+| `LoggingMessageNotification` | `LoggingMessageNotification.builder().level(l).data(d)` | `LoggingMessageNotification.builder(l, d)` |
+
+Two records that previously had no builder now have one with the same required-first convention:
+
+- `ProgressNotification.builder(progressToken, progress)` — optional: `.total(Double)`, `.message(String)`, `.meta(Map)`
+- `JSONRPCResponse.JSONRPCError.builder(code, message)` — optional: `.data(Object)`
+
+**Note:** `LoggingMessageNotification.level` must never be `null`. Because `LoggingLevel` deserialization is lenient (see the `LoggingLevel` section above), callers should ensure clients and servers send only recognized level strings.
+
 ### Optional JSON Schema validation on `tools/call` (server)
 
 When a `JsonSchemaValidator` is available (including the default from `McpJsonDefaults.getSchemaValidator()` when you do not configure one explicitly) and `validateToolInputs` is left at its default of `true`, the server validates incoming tool arguments against `tool.inputSchema()` before invoking the tool. Failed validation produces a `CallToolResult` with `isError` set and a textual error in the content.
diff --git a/conformance-tests/server-servlet/src/main/java/io/modelcontextprotocol/conformance/server/ConformanceServlet.java b/conformance-tests/server-servlet/src/main/java/io/modelcontextprotocol/conformance/server/ConformanceServlet.java
index 25ec2c106..71704e2a7 100644
--- a/conformance-tests/server-servlet/src/main/java/io/modelcontextprotocol/conformance/server/ConformanceServlet.java
+++ b/conformance-tests/server-servlet/src/main/java/io/modelcontextprotocol/conformance/server/ConformanceServlet.java
@@ -237,18 +237,14 @@ private static List<McpServerFeatures.SyncToolSpecification> createToolSpecs() {
 					.callHandler((exchange, request) -> {
 						logger.info("Tool 'test_tool_with_logging' called");
 						// Send log notifications
-						exchange.loggingNotification(LoggingMessageNotification.builder()
-							.level(LoggingLevel.INFO)
-							.data("Tool execution started")
-							.build());
-						exchange.loggingNotification(LoggingMessageNotification.builder()
-							.level(LoggingLevel.INFO)
-							.data("Tool processing data")
-							.build());
-						exchange.loggingNotification(LoggingMessageNotification.builder()
-							.level(LoggingLevel.INFO)
-							.data("Tool execution completed")
-							.build());
+						exchange.loggingNotification(
+								LoggingMessageNotification.builder(LoggingLevel.INFO, "Tool execution started")
+									.build());
+						exchange.loggingNotification(
+								LoggingMessageNotification.builder(LoggingLevel.INFO, "Tool processing data").build());
+						exchange.loggingNotification(
+								LoggingMessageNotification.builder(LoggingLevel.INFO, "Tool execution completed")
+									.build());
 						return CallToolResult.builder()
 							.content(List.of(new TextContent("Tool execution completed with logging")))
 							.isError(false)
@@ -335,9 +331,8 @@ private static List<McpServerFeatures.SyncToolSpecification> createToolSpecs() {
 						String prompt = (String) request.arguments().get("prompt");
 
 						// Request sampling from client
-						CreateMessageRequest samplingRequest = CreateMessageRequest.builder()
-							.messages(List.of(new SamplingMessage(Role.USER, new TextContent(prompt))))
-							.maxTokens(100)
+						CreateMessageRequest samplingRequest = CreateMessageRequest
+							.builder(List.of(new SamplingMessage(Role.USER, new TextContent(prompt))), 100)
 							.build();
 
 						CreateMessageResult response = exchange.createMessage(samplingRequest);
diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/spec/McpSchema.java b/mcp-core/src/main/java/io/modelcontextprotocol/spec/McpSchema.java
index 72376929c..abd6e0ff9 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/spec/McpSchema.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/spec/McpSchema.java
@@ -296,6 +296,41 @@ public record JSONRPCError( // @formatter:off
 			@JsonProperty("code") Integer code,
 			@JsonProperty("message") String message,
 			@JsonProperty("data") Object data) { // @formatter:on
+
+			public JSONRPCError {
+				Assert.notNull(code, "code must not be null");
+				Assert.notNull(message, "message must not be null");
+			}
+
+			public static Builder builder(int code, String message) {
+				return new Builder(code, message);
+			}
+
+			public static class Builder {
+
+				private final Integer code;
+
+				private final String message;
+
+				private Object data;
+
+				private Builder(int code, String message) {
+					Assert.notNull(message, "message must not be null");
+					this.code = code;
+					this.message = message;
+				}
+
+				public Builder data(Object data) {
+					this.data = data;
+					return this;
+				}
+
+				public JSONRPCError build() {
+					return new JSONRPCError(code, message, data);
+				}
+
+			}
+
 		}
 	}
 
@@ -1573,6 +1608,10 @@ public record CallToolResult( // @formatter:off
 		@JsonProperty("structuredContent") Object structuredContent,
 		@JsonProperty("_meta") Map<String, Object> meta) implements Result { // @formatter:on
 
+		public CallToolResult {
+			Assert.notNull(content, "content must not be null");
+		}
+
 		/**
 		 * Creates a builder for {@link CallToolResult}.
 		 * @return a new builder instance
@@ -1590,6 +1629,14 @@ public static class Builder {
 
 			private Boolean isError = false;
 
+			/**
+			 * @deprecated Use {@link CallToolResult#builder()} factory method instead of
+			 * instantiating the builder directly.
+			 */
+			@Deprecated
+			public Builder() {
+			}
+
 			private Object structuredContent;
 
 			private Map<String, Object> meta;
@@ -1683,6 +1730,7 @@ public Builder meta(Map<String, Object> meta) {
 			 * @return a new CallToolResult instance
 			 */
 			public CallToolResult build() {
+				Assert.notNull(content, "content must not be null");
 				return new CallToolResult(content, isError, structuredContent, meta);
 			}
 
@@ -1797,6 +1845,11 @@ public static ModelHint of(String name) {
 	public record SamplingMessage( // @formatter:off
 		@JsonProperty("role") Role role,
 		@JsonProperty("content") Content content) { // @formatter:on
+
+		public SamplingMessage {
+			Assert.notNull(role, "role must not be null");
+			Assert.notNull(content, "content must not be null");
+		}
 	}
 
 	/**
@@ -1834,6 +1887,11 @@ public record CreateMessageRequest( // @formatter:off
 		@JsonProperty("metadata") Map<String, Object> metadata,
 		@JsonProperty("_meta") Map<String, Object> meta) implements Request { // @formatter:on
 
+		public CreateMessageRequest {
+			Assert.notNull(messages, "messages must not be null");
+			Assert.notNull(maxTokens, "maxTokens must not be null");
+		}
+
 		// backwards compatibility constructor
 		public CreateMessageRequest(List<SamplingMessage> messages, ModelPreferences modelPreferences,
 				String systemPrompt, ContextInclusionStrategy includeContext, Double temperature, Integer maxTokens,
@@ -1851,10 +1909,18 @@ public enum ContextInclusionStrategy {
 
 		}
 
+		/**
+		 * @deprecated Use {@link #builder(List, int)} instead.
+		 */
+		@Deprecated
 		public static Builder builder() {
 			return new Builder();
 		}
 
+		public static Builder builder(List<SamplingMessage> messages, int maxTokens) {
+			return new Builder(messages, maxTokens);
+		}
+
 		public static class Builder {
 
 			private List<SamplingMessage> messages;
@@ -1875,7 +1941,22 @@ public static class Builder {
 
 			private Map<String, Object> meta;
 
+			/**
+			 * @deprecated Use {@link CreateMessageRequest#builder(List, int)} factory
+			 * method instead.
+			 */
+			@Deprecated
+			public Builder() {
+			}
+
+			private Builder(List<SamplingMessage> messages, int maxTokens) {
+				Assert.notNull(messages, "messages must not be null");
+				this.messages = messages;
+				this.maxTokens = maxTokens;
+			}
+
 			public Builder messages(List<SamplingMessage> messages) {
+				Assert.notNull(messages, "messages must not be null");
 				this.messages = messages;
 				return this;
 			}
@@ -2063,15 +2144,28 @@ public record ElicitRequest( // @formatter:off
 		@JsonProperty("requestedSchema") Map<String, Object> requestedSchema,
 		@JsonProperty("_meta") Map<String, Object> meta) implements Request { // @formatter:on
 
+		public ElicitRequest {
+			Assert.notNull(message, "message must not be null");
+			Assert.notNull(requestedSchema, "requestedSchema must not be null");
+		}
+
 		// backwards compatibility constructor
 		public ElicitRequest(String message, Map<String, Object> requestedSchema) {
 			this(message, requestedSchema, null);
 		}
 
+		/**
+		 * @deprecated Use {@link #builder(String, Map)} instead.
+		 */
+		@Deprecated
 		public static Builder builder() {
 			return new Builder();
 		}
 
+		public static Builder builder(String message, Map<String, Object> requestedSchema) {
+			return new Builder(message, requestedSchema);
+		}
+
 		public static class Builder {
 
 			private String message;
@@ -2080,12 +2174,29 @@ public static class Builder {
 
 			private Map<String, Object> meta;
 
+			/**
+			 * @deprecated Use {@link ElicitRequest#builder(String, Map)} factory method
+			 * instead.
+			 */
+			@Deprecated
+			public Builder() {
+			}
+
+			private Builder(String message, Map<String, Object> requestedSchema) {
+				Assert.notNull(message, "message must not be null");
+				Assert.notNull(requestedSchema, "requestedSchema must not be null");
+				this.message = message;
+				this.requestedSchema = requestedSchema;
+			}
+
 			public Builder message(String message) {
+				Assert.notNull(message, "message must not be null");
 				this.message = message;
 				return this;
 			}
 
 			public Builder requestedSchema(Map<String, Object> requestedSchema) {
+				Assert.notNull(requestedSchema, "requestedSchema must not be null");
 				this.requestedSchema = requestedSchema;
 				return this;
 			}
@@ -2239,9 +2350,58 @@ public record ProgressNotification( // @formatter:off
 		@JsonProperty("message") String message,
 		@JsonProperty("_meta") Map<String, Object> meta) implements Notification { // @formatter:on
 
+		public ProgressNotification {
+			Assert.notNull(progressToken, "progressToken must not be null");
+			Assert.notNull(progress, "progress must not be null");
+		}
+
 		public ProgressNotification(Object progressToken, double progress, Double total, String message) {
 			this(progressToken, progress, total, message, null);
 		}
+
+		public static Builder builder(Object progressToken, double progress) {
+			return new Builder(progressToken, progress);
+		}
+
+		public static class Builder {
+
+			private final Object progressToken;
+
+			private final Double progress;
+
+			private Double total;
+
+			private String message;
+
+			private Map<String, Object> meta;
+
+			private Builder(Object progressToken, double progress) {
+				Assert.notNull(progressToken, "progressToken must not be null");
+				this.progressToken = progressToken;
+				this.progress = progress;
+			}
+
+			public Builder total(Double total) {
+				this.total = total;
+				return this;
+			}
+
+			public Builder message(String message) {
+				this.message = message;
+				return this;
+			}
+
+			public Builder meta(Map<String, Object> meta) {
+				this.meta = meta;
+				return this;
+			}
+
+			public ProgressNotification build() {
+				return new ProgressNotification(progressToken, progress, total, message, meta);
+			}
+
+		}
+
 	}
 
 	/**
@@ -2281,15 +2441,28 @@ public record LoggingMessageNotification( // @formatter:off
 		@JsonProperty("data") String data,
 		@JsonProperty("_meta") Map<String, Object> meta) implements Notification { // @formatter:on
 
+		public LoggingMessageNotification {
+			Assert.notNull(level, "level must not be null");
+			Assert.notNull(data, "data must not be null");
+		}
+
 		// backwards compatibility constructor
 		public LoggingMessageNotification(LoggingLevel level, String logger, String data) {
 			this(level, logger, data, null);
 		}
 
+		/**
+		 * @deprecated Use {@link #builder(LoggingLevel, String)} instead.
+		 */
+		@Deprecated
 		public static Builder builder() {
 			return new Builder();
 		}
 
+		public static Builder builder(LoggingLevel level, String data) {
+			return new Builder(level, data);
+		}
+
 		public static class Builder {
 
 			private LoggingLevel level = LoggingLevel.INFO;
@@ -2300,7 +2473,24 @@ public static class Builder {
 
 			private Map<String, Object> meta;
 
+			/**
+			 * @deprecated Use
+			 * {@link LoggingMessageNotification#builder(LoggingLevel, String)} factory
+			 * method instead.
+			 */
+			@Deprecated
+			public Builder() {
+			}
+
+			private Builder(LoggingLevel level, String data) {
+				Assert.notNull(level, "level must not be null");
+				Assert.notNull(data, "data must not be null");
+				this.level = level;
+				this.data = data;
+			}
+
 			public Builder level(LoggingLevel level) {
+				Assert.notNull(level, "level must not be null");
 				this.level = level;
 				return this;
 			}
@@ -2311,6 +2501,7 @@ public Builder logger(String logger) {
 			}
 
 			public Builder data(String data) {
+				Assert.notNull(data, "data must not be null");
 				this.data = data;
 				return this;
 			}
diff --git a/mcp-core/src/test/java/io/modelcontextprotocol/server/McpAsyncServerExchangeTests.java b/mcp-core/src/test/java/io/modelcontextprotocol/server/McpAsyncServerExchangeTests.java
index e6161a59f..5f07b318c 100644
--- a/mcp-core/src/test/java/io/modelcontextprotocol/server/McpAsyncServerExchangeTests.java
+++ b/mcp-core/src/test/java/io/modelcontextprotocol/server/McpAsyncServerExchangeTests.java
@@ -227,10 +227,9 @@ void testSetMinLoggingLevelWithNullValue() {
 
 	@Test
 	void testLoggingNotificationWithAllowedLevel() {
-		McpSchema.LoggingMessageNotification notification = McpSchema.LoggingMessageNotification.builder()
-			.level(McpSchema.LoggingLevel.ERROR)
+		McpSchema.LoggingMessageNotification notification = McpSchema.LoggingMessageNotification
+			.builder(McpSchema.LoggingLevel.ERROR, "Test error message")
 			.logger("test-logger")
-			.data("Test error message")
 			.build();
 
 		when(mockSession.isNotificationForLevelAllowed(any())).thenReturn(Boolean.TRUE);
@@ -248,10 +247,9 @@ void testLoggingNotificationWithFilteredLevel() {
 		exchange.setMinLoggingLevel(McpSchema.LoggingLevel.DEBUG);
 		verify(mockSession, times(1)).setMinLoggingLevel(eq(McpSchema.LoggingLevel.DEBUG));
 
-		McpSchema.LoggingMessageNotification debugNotification = McpSchema.LoggingMessageNotification.builder()
-			.level(McpSchema.LoggingLevel.DEBUG)
+		McpSchema.LoggingMessageNotification debugNotification = McpSchema.LoggingMessageNotification
+			.builder(McpSchema.LoggingLevel.DEBUG, "Debug message that should be filtered")
 			.logger("test-logger")
-			.data("Debug message that should be filtered")
 			.build();
 
 		when(mockSession.isNotificationForLevelAllowed(eq(McpSchema.LoggingLevel.DEBUG))).thenReturn(Boolean.TRUE);
@@ -264,10 +262,9 @@ void testLoggingNotificationWithFilteredLevel() {
 		verify(mockSession, times(1)).sendNotification(eq(McpSchema.METHOD_NOTIFICATION_MESSAGE),
 				eq(debugNotification));
 
-		McpSchema.LoggingMessageNotification warningNotification = McpSchema.LoggingMessageNotification.builder()
-			.level(McpSchema.LoggingLevel.WARNING)
+		McpSchema.LoggingMessageNotification warningNotification = McpSchema.LoggingMessageNotification
+			.builder(McpSchema.LoggingLevel.WARNING, "Debug message that should be filtered")
 			.logger("test-logger")
-			.data("Debug message that should be filtered")
 			.build();
 
 		StepVerifier.create(exchange.loggingNotification(warningNotification)).verifyComplete();
@@ -279,10 +276,9 @@ void testLoggingNotificationWithFilteredLevel() {
 
 	@Test
 	void testLoggingNotificationWithSessionError() {
-		McpSchema.LoggingMessageNotification notification = McpSchema.LoggingMessageNotification.builder()
-			.level(McpSchema.LoggingLevel.ERROR)
+		McpSchema.LoggingMessageNotification notification = McpSchema.LoggingMessageNotification
+			.builder(McpSchema.LoggingLevel.ERROR, "Test error message")
 			.logger("test-logger")
-			.data("Test error message")
 			.build();
 
 		when(mockSession.isNotificationForLevelAllowed(any())).thenReturn(Boolean.TRUE);
@@ -304,8 +300,8 @@ void testCreateElicitationWithNullCapabilities() {
 		McpAsyncServerExchange exchangeWithNullCapabilities = new McpAsyncServerExchange("testSessionId", mockSession,
 				null, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your name")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your name", Map.of("type", "object"))
 			.build();
 
 		StepVerifier.create(exchangeWithNullCapabilities.createElicitation(elicitRequest))
@@ -328,8 +324,8 @@ void testCreateElicitationWithoutElicitationCapabilities() {
 		McpAsyncServerExchange exchangeWithoutElicitation = new McpAsyncServerExchange("testSessionId", mockSession,
 				capabilitiesWithoutElicitation, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your name")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your name", Map.of("type", "object"))
 			.build();
 
 		StepVerifier.create(exchangeWithoutElicitation.createElicitation(elicitRequest)).verifyErrorSatisfies(error -> {
@@ -359,9 +355,8 @@ void testCreateElicitationWithComplexRequest() {
 				java.util.Map.of("type", "number")));
 		requestedSchema.put("required", java.util.List.of("name"));
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your personal information")
-			.requestedSchema(requestedSchema)
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your personal information", requestedSchema)
 			.build();
 
 		java.util.Map<String, Object> responseContent = new java.util.HashMap<>();
@@ -395,8 +390,8 @@ void testCreateElicitationWithDeclineAction() {
 		McpAsyncServerExchange exchangeWithElicitation = new McpAsyncServerExchange("testSessionId", mockSession,
 				capabilitiesWithElicitation, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide sensitive information")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide sensitive information", Map.of("type", "object"))
 			.build();
 
 		McpSchema.ElicitResult expectedResult = McpSchema.ElicitResult.builder()
@@ -422,8 +417,8 @@ void testCreateElicitationWithCancelAction() {
 		McpAsyncServerExchange exchangeWithElicitation = new McpAsyncServerExchange("testSessionId", mockSession,
 				capabilitiesWithElicitation, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your information")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your information", Map.of("type", "object"))
 			.build();
 
 		McpSchema.ElicitResult expectedResult = McpSchema.ElicitResult.builder()
@@ -449,8 +444,8 @@ void testCreateElicitationWithSessionError() {
 		McpAsyncServerExchange exchangeWithElicitation = new McpAsyncServerExchange("testSessionId", mockSession,
 				capabilitiesWithElicitation, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your name")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your name", Map.of("type", "object"))
 			.build();
 
 		when(mockSession.sendRequest(eq(McpSchema.METHOD_ELICITATION_CREATE), eq(elicitRequest), any(TypeRef.class)))
@@ -471,9 +466,10 @@ void testCreateMessageWithNullCapabilities() {
 		McpAsyncServerExchange exchangeWithNullCapabilities = new McpAsyncServerExchange("testSessionId", mockSession,
 				null, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays
-				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(Arrays
+				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))),
+					1000)
 			.build();
 
 		StepVerifier.create(exchangeWithNullCapabilities.createMessage(createMessageRequest))
@@ -497,9 +493,10 @@ void testCreateMessageWithoutSamplingCapabilities() {
 		McpAsyncServerExchange exchangeWithoutSampling = new McpAsyncServerExchange("testSessionId", mockSession,
 				capabilitiesWithoutSampling, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays
-				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(Arrays
+				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))),
+					1000)
 			.build();
 
 		StepVerifier.create(exchangeWithoutSampling.createMessage(createMessageRequest)).verifyErrorSatisfies(error -> {
@@ -522,9 +519,10 @@ void testCreateMessageWithBasicRequest() {
 		McpAsyncServerExchange exchangeWithSampling = new McpAsyncServerExchange("testSessionId", mockSession,
 				capabilitiesWithSampling, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays
-				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(Arrays
+				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))),
+					1000)
 			.build();
 
 		McpSchema.CreateMessageResult expectedResult = McpSchema.CreateMessageResult.builder()
@@ -559,10 +557,13 @@ void testCreateMessageWithImageContent() {
 				capabilitiesWithSampling, clientInfo, McpTransportContext.EMPTY);
 
 		// Create request with image content
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER,
-					new McpSchema.ImageContent(null, "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD...",
-							"image/jpeg"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(
+					Arrays
+						.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER,
+								new McpSchema.ImageContent(null,
+										"data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD...", "image/jpeg"))),
+					1000)
 			.build();
 
 		McpSchema.CreateMessageResult expectedResult = McpSchema.CreateMessageResult.builder()
@@ -593,9 +594,11 @@ void testCreateMessageWithSessionError() {
 		McpAsyncServerExchange exchangeWithSampling = new McpAsyncServerExchange("testSessionId", mockSession,
 				capabilitiesWithSampling, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays
-				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(
+					Arrays
+						.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello"))),
+					1000)
 			.build();
 
 		when(mockSession.sendRequest(eq(McpSchema.METHOD_SAMPLING_CREATE_MESSAGE), eq(createMessageRequest),
@@ -617,9 +620,9 @@ void testCreateMessageWithIncludeContext() {
 		McpAsyncServerExchange exchangeWithSampling = new McpAsyncServerExchange("testSessionId", mockSession,
 				capabilitiesWithSampling, clientInfo, McpTransportContext.EMPTY);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER,
-					new McpSchema.TextContent("What files are available?"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(Arrays.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER,
+					new McpSchema.TextContent("What files are available?"))), 1000)
 			.includeContext(McpSchema.CreateMessageRequest.ContextInclusionStrategy.ALL_SERVERS)
 			.build();
 
diff --git a/mcp-core/src/test/java/io/modelcontextprotocol/server/McpSyncServerExchangeTests.java b/mcp-core/src/test/java/io/modelcontextprotocol/server/McpSyncServerExchangeTests.java
index fba733c9a..009a17955 100644
--- a/mcp-core/src/test/java/io/modelcontextprotocol/server/McpSyncServerExchangeTests.java
+++ b/mcp-core/src/test/java/io/modelcontextprotocol/server/McpSyncServerExchangeTests.java
@@ -221,10 +221,9 @@ void testLoggingNotificationWithNullMessage() {
 	@Test
 	void testLoggingNotificationWithAllowedLevel() {
 
-		McpSchema.LoggingMessageNotification notification = McpSchema.LoggingMessageNotification.builder()
-			.level(McpSchema.LoggingLevel.ERROR)
+		McpSchema.LoggingMessageNotification notification = McpSchema.LoggingMessageNotification
+			.builder(McpSchema.LoggingLevel.ERROR, "Test error message")
 			.logger("test-logger")
-			.data("Test error message")
 			.build();
 
 		when(mockSession.isNotificationForLevelAllowed(any())).thenReturn(Boolean.TRUE);
@@ -243,10 +242,9 @@ void testLoggingNotificationWithFilteredLevel() {
 		asyncExchange.setMinLoggingLevel(McpSchema.LoggingLevel.DEBUG);
 		verify(mockSession, times(1)).setMinLoggingLevel(McpSchema.LoggingLevel.DEBUG);
 
-		McpSchema.LoggingMessageNotification debugNotification = McpSchema.LoggingMessageNotification.builder()
-			.level(McpSchema.LoggingLevel.DEBUG)
+		McpSchema.LoggingMessageNotification debugNotification = McpSchema.LoggingMessageNotification
+			.builder(McpSchema.LoggingLevel.DEBUG, "Debug message that should be filtered")
 			.logger("test-logger")
-			.data("Debug message that should be filtered")
 			.build();
 
 		when(mockSession.isNotificationForLevelAllowed(eq(McpSchema.LoggingLevel.DEBUG))).thenReturn(Boolean.TRUE);
@@ -259,10 +257,9 @@ void testLoggingNotificationWithFilteredLevel() {
 		verify(mockSession, times(1)).sendNotification(eq(McpSchema.METHOD_NOTIFICATION_MESSAGE),
 				eq(debugNotification));
 
-		McpSchema.LoggingMessageNotification warningNotification = McpSchema.LoggingMessageNotification.builder()
-			.level(McpSchema.LoggingLevel.WARNING)
+		McpSchema.LoggingMessageNotification warningNotification = McpSchema.LoggingMessageNotification
+			.builder(McpSchema.LoggingLevel.WARNING, "Debug message that should be filtered")
 			.logger("test-logger")
-			.data("Debug message that should be filtered")
 			.build();
 
 		exchange.loggingNotification(warningNotification);
@@ -275,10 +272,9 @@ void testLoggingNotificationWithFilteredLevel() {
 	@Test
 	void testLoggingNotificationWithSessionError() {
 
-		McpSchema.LoggingMessageNotification notification = McpSchema.LoggingMessageNotification.builder()
-			.level(McpSchema.LoggingLevel.ERROR)
+		McpSchema.LoggingMessageNotification notification = McpSchema.LoggingMessageNotification
+			.builder(McpSchema.LoggingLevel.ERROR, "Test error message")
 			.logger("test-logger")
-			.data("Test error message")
 			.build();
 
 		when(mockSession.isNotificationForLevelAllowed(any())).thenReturn(Boolean.TRUE);
@@ -301,8 +297,8 @@ void testCreateElicitationWithNullCapabilities() {
 		McpSyncServerExchange exchangeWithNullCapabilities = new McpSyncServerExchange(
 				asyncExchangeWithNullCapabilities);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your name")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your name", Map.of("type", "object"))
 			.build();
 
 		assertThatThrownBy(() -> exchangeWithNullCapabilities.createElicitation(elicitRequest))
@@ -324,8 +320,8 @@ void testCreateElicitationWithoutElicitationCapabilities() {
 				mockSession, capabilitiesWithoutElicitation, clientInfo, McpTransportContext.EMPTY);
 		McpSyncServerExchange exchangeWithoutElicitation = new McpSyncServerExchange(asyncExchangeWithoutElicitation);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your name")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your name", Map.of("type", "object"))
 			.build();
 
 		assertThatThrownBy(() -> exchangeWithoutElicitation.createElicitation(elicitRequest))
@@ -355,9 +351,8 @@ void testCreateElicitationWithComplexRequest() {
 				java.util.Map.of("type", "number")));
 		requestedSchema.put("required", java.util.List.of("name"));
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your personal information")
-			.requestedSchema(requestedSchema)
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your personal information", requestedSchema)
 			.build();
 
 		java.util.Map<String, Object> responseContent = new java.util.HashMap<>();
@@ -392,8 +387,8 @@ void testCreateElicitationWithDeclineAction() {
 				capabilitiesWithElicitation, clientInfo, McpTransportContext.EMPTY);
 		McpSyncServerExchange exchangeWithElicitation = new McpSyncServerExchange(asyncExchangeWithElicitation);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide sensitive information")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide sensitive information", Map.of("type", "object"))
 			.build();
 
 		McpSchema.ElicitResult expectedResult = McpSchema.ElicitResult.builder()
@@ -420,8 +415,8 @@ void testCreateElicitationWithCancelAction() {
 				capabilitiesWithElicitation, clientInfo, McpTransportContext.EMPTY);
 		McpSyncServerExchange exchangeWithElicitation = new McpSyncServerExchange(asyncExchangeWithElicitation);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your information")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your information", Map.of("type", "object"))
 			.build();
 
 		McpSchema.ElicitResult expectedResult = McpSchema.ElicitResult.builder()
@@ -448,8 +443,8 @@ void testCreateElicitationWithSessionError() {
 				capabilitiesWithElicitation, clientInfo, McpTransportContext.EMPTY);
 		McpSyncServerExchange exchangeWithElicitation = new McpSyncServerExchange(asyncExchangeWithElicitation);
 
-		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Please provide your name")
+		McpSchema.ElicitRequest elicitRequest = McpSchema.ElicitRequest
+			.builder("Please provide your name", Map.of("type", "object"))
 			.build();
 
 		when(mockSession.sendRequest(eq(McpSchema.METHOD_ELICITATION_CREATE), eq(elicitRequest), any(TypeRef.class)))
@@ -472,9 +467,10 @@ void testCreateMessageWithNullCapabilities() {
 		McpSyncServerExchange exchangeWithNullCapabilities = new McpSyncServerExchange(
 				asyncExchangeWithNullCapabilities);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays
-				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(Arrays
+				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))),
+					1000)
 			.build();
 
 		assertThatThrownBy(() -> exchangeWithNullCapabilities.createMessage(createMessageRequest))
@@ -497,9 +493,10 @@ void testCreateMessageWithoutSamplingCapabilities() {
 				capabilitiesWithoutSampling, clientInfo, McpTransportContext.EMPTY);
 		McpSyncServerExchange exchangeWithoutSampling = new McpSyncServerExchange(asyncExchangeWithoutSampling);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays
-				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(Arrays
+				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))),
+					1000)
 			.build();
 
 		assertThatThrownBy(() -> exchangeWithoutSampling.createMessage(createMessageRequest))
@@ -522,9 +519,10 @@ void testCreateMessageWithBasicRequest() {
 				capabilitiesWithSampling, clientInfo, McpTransportContext.EMPTY);
 		McpSyncServerExchange exchangeWithSampling = new McpSyncServerExchange(asyncExchangeWithSampling);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays
-				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(Arrays
+				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello, world!"))),
+					1000)
 			.build();
 
 		McpSchema.CreateMessageResult expectedResult = McpSchema.CreateMessageResult.builder()
@@ -560,10 +558,13 @@ void testCreateMessageWithImageContent() {
 		McpSyncServerExchange exchangeWithSampling = new McpSyncServerExchange(asyncExchangeWithSampling);
 
 		// Create request with image content
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER,
-					new McpSchema.ImageContent(null, "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD...",
-							"image/jpeg"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(
+					Arrays
+						.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER,
+								new McpSchema.ImageContent(null,
+										"data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD...", "image/jpeg"))),
+					1000)
 			.build();
 
 		McpSchema.CreateMessageResult expectedResult = McpSchema.CreateMessageResult.builder()
@@ -595,9 +596,11 @@ void testCreateMessageWithSessionError() {
 				capabilitiesWithSampling, clientInfo, McpTransportContext.EMPTY);
 		McpSyncServerExchange exchangeWithSampling = new McpSyncServerExchange(asyncExchangeWithSampling);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays
-				.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(
+					Arrays
+						.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER, new McpSchema.TextContent("Hello"))),
+					1000)
 			.build();
 
 		when(mockSession.sendRequest(eq(McpSchema.METHOD_SAMPLING_CREATE_MESSAGE), eq(createMessageRequest),
@@ -620,9 +623,9 @@ void testCreateMessageWithIncludeContext() {
 				capabilitiesWithSampling, clientInfo, McpTransportContext.EMPTY);
 		McpSyncServerExchange exchangeWithSampling = new McpSyncServerExchange(asyncExchangeWithSampling);
 
-		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest.builder()
-			.messages(Arrays.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER,
-					new McpSchema.TextContent("What files are available?"))))
+		McpSchema.CreateMessageRequest createMessageRequest = McpSchema.CreateMessageRequest
+			.builder(Arrays.asList(new McpSchema.SamplingMessage(McpSchema.Role.USER,
+					new McpSchema.TextContent("What files are available?"))), 1000)
 			.includeContext(McpSchema.CreateMessageRequest.ContextInclusionStrategy.ALL_SERVERS)
 			.build();
 
diff --git a/mcp-test/src/main/java/io/modelcontextprotocol/AbstractMcpClientServerIntegrationTests.java b/mcp-test/src/main/java/io/modelcontextprotocol/AbstractMcpClientServerIntegrationTests.java
index beec006ba..7675f4e36 100644
--- a/mcp-test/src/main/java/io/modelcontextprotocol/AbstractMcpClientServerIntegrationTests.java
+++ b/mcp-test/src/main/java/io/modelcontextprotocol/AbstractMcpClientServerIntegrationTests.java
@@ -162,9 +162,9 @@ void testCreateMessageSuccess(String clientType) {
 			.tool(Tool.builder().name("tool1").description("tool1 description").inputSchema(EMPTY_JSON_SCHEMA).build())
 			.callHandler((exchange, request) -> {
 
-				var createMessageRequest = McpSchema.CreateMessageRequest.builder()
-					.messages(List.of(new McpSchema.SamplingMessage(McpSchema.Role.USER,
-							new McpSchema.TextContent("Test message"))))
+				var createMessageRequest = McpSchema.CreateMessageRequest
+					.builder(List.of(new McpSchema.SamplingMessage(McpSchema.Role.USER,
+							new McpSchema.TextContent("Test message"))), 1000)
 					.modelPreferences(ModelPreferences.builder()
 						.hints(List.of())
 						.costPriority(1.0)
@@ -241,9 +241,9 @@ void testCreateMessageWithRequestTimeoutSuccess(String clientType) throws Interr
 			.tool(Tool.builder().name("tool1").description("tool1 description").inputSchema(EMPTY_JSON_SCHEMA).build())
 			.callHandler((exchange, request) -> {
 
-				var createMessageRequest = McpSchema.CreateMessageRequest.builder()
-					.messages(List.of(new McpSchema.SamplingMessage(McpSchema.Role.USER,
-							new McpSchema.TextContent("Test message"))))
+				var createMessageRequest = McpSchema.CreateMessageRequest
+					.builder(List.of(new McpSchema.SamplingMessage(McpSchema.Role.USER,
+							new McpSchema.TextContent("Test message"))), 1000)
 					.modelPreferences(ModelPreferences.builder()
 						.hints(List.of())
 						.costPriority(1.0)
@@ -316,9 +316,9 @@ void testCreateMessageWithRequestTimeoutFail(String clientType) throws Interrupt
 			.tool(Tool.builder().name("tool1").description("tool1 description").inputSchema(EMPTY_JSON_SCHEMA).build())
 			.callHandler((exchange, request) -> {
 
-				var createMessageRequest = McpSchema.CreateMessageRequest.builder()
-					.messages(List.of(new McpSchema.SamplingMessage(McpSchema.Role.USER,
-							new McpSchema.TextContent("Test message"))))
+				var createMessageRequest = McpSchema.CreateMessageRequest
+					.builder(List.of(new McpSchema.SamplingMessage(McpSchema.Role.USER,
+							new McpSchema.TextContent("Test message"))), 1000)
 					.modelPreferences(ModelPreferences.builder()
 						.hints(List.of())
 						.costPriority(1.0)
@@ -412,9 +412,8 @@ void testCreateElicitationSuccess(String clientType) {
 			.tool(Tool.builder().name("tool1").description("tool1 description").inputSchema(EMPTY_JSON_SCHEMA).build())
 			.callHandler((exchange, request) -> {
 
-				var elicitationRequest = McpSchema.ElicitRequest.builder()
-					.message("Test message")
-					.requestedSchema(
+				var elicitationRequest = McpSchema.ElicitRequest
+					.builder("Test message",
 							Map.of("type", "object", "properties", Map.of("message", Map.of("type", "string"))))
 					.build();
 
@@ -471,9 +470,8 @@ void testCreateElicitationWithRequestTimeoutSuccess(String clientType) {
 			.tool(Tool.builder().name("tool1").description("tool1 description").inputSchema(EMPTY_JSON_SCHEMA).build())
 			.callHandler((exchange, request) -> {
 
-				var elicitationRequest = McpSchema.ElicitRequest.builder()
-					.message("Test message")
-					.requestedSchema(
+				var elicitationRequest = McpSchema.ElicitRequest
+					.builder("Test message",
 							Map.of("type", "object", "properties", Map.of("message", Map.of("type", "string"))))
 					.build();
 
@@ -542,9 +540,8 @@ void testCreateElicitationWithRequestTimeoutFail(String clientType) {
 			.tool(Tool.builder().name("tool1").description("tool1 description").inputSchema(EMPTY_JSON_SCHEMA).build())
 			.callHandler((exchange, request) -> {
 
-				var elicitationRequest = ElicitRequest.builder()
-					.message("Test message")
-					.requestedSchema(
+				var elicitationRequest = ElicitRequest
+					.builder("Test message",
 							Map.of("type", "object", "properties", Map.of("message", Map.of("type", "string"))))
 					.build();
 
@@ -1113,34 +1110,29 @@ void testLoggingNotification(String clientType) throws InterruptedException {
 
 			//@formatter:off
 					return exchange // This should be filtered out (DEBUG < NOTICE)
-						.loggingNotification(McpSchema.LoggingMessageNotification.builder()
-								.level(McpSchema.LoggingLevel.DEBUG)
+						.loggingNotification(McpSchema.LoggingMessageNotification
+								.builder(McpSchema.LoggingLevel.DEBUG, "Debug message")
 								.logger("test-logger")
-								.data("Debug message")
 								.build())
 					.then(exchange // This should be sent (NOTICE >= NOTICE)
-						.loggingNotification(McpSchema.LoggingMessageNotification.builder()
-								.level(McpSchema.LoggingLevel.NOTICE)
+						.loggingNotification(McpSchema.LoggingMessageNotification
+								.builder(McpSchema.LoggingLevel.NOTICE, "Notice message")
 								.logger("test-logger")
-								.data("Notice message")
 								.build()))
 					.then(exchange // This should be sent (ERROR > NOTICE)
-						.loggingNotification(McpSchema.LoggingMessageNotification.builder()
-							.level(McpSchema.LoggingLevel.ERROR)
+						.loggingNotification(McpSchema.LoggingMessageNotification
+							.builder(McpSchema.LoggingLevel.ERROR, "Error message")
 							.logger("test-logger")
-							.data("Error message")
 							.build()))
 					.then(exchange // This should be filtered out (INFO < NOTICE)
-						.loggingNotification(McpSchema.LoggingMessageNotification.builder()
-								.level(McpSchema.LoggingLevel.INFO)
+						.loggingNotification(McpSchema.LoggingMessageNotification
+								.builder(McpSchema.LoggingLevel.INFO, "Another info message")
 								.logger("test-logger")
-								.data("Another info message")
 								.build()))
 					.then(exchange // This should be sent (ERROR >= NOTICE)
-						.loggingNotification(McpSchema.LoggingMessageNotification.builder()
-								.level(McpSchema.LoggingLevel.ERROR)
+						.loggingNotification(McpSchema.LoggingMessageNotification
+								.builder(McpSchema.LoggingLevel.ERROR, "Another error message")
 								.logger("test-logger")
-								.data("Another error message")
 								.build()))
 					.thenReturn(CallToolResult.builder()
 						.content(List.of(new McpSchema.TextContent("Logging test completed")))
diff --git a/mcp-test/src/test/java/io/modelcontextprotocol/client/McpAsyncClientResponseHandlerTests.java b/mcp-test/src/test/java/io/modelcontextprotocol/client/McpAsyncClientResponseHandlerTests.java
index 47a229afd..3692c1c4e 100644
--- a/mcp-test/src/test/java/io/modelcontextprotocol/client/McpAsyncClientResponseHandlerTests.java
+++ b/mcp-test/src/test/java/io/modelcontextprotocol/client/McpAsyncClientResponseHandlerTests.java
@@ -417,9 +417,9 @@ void testElicitationCreateRequestHandling() {
 		assertThat(asyncMcpClient.initialize().block()).isNotNull();
 
 		// Create a mock elicitation
-		var elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Test message")
-			.requestedSchema(Map.of("type", "object", "properties", Map.of("message", Map.of("type", "string"))))
+		var elicitRequest = McpSchema.ElicitRequest
+			.builder("Test message",
+					Map.of("type", "object", "properties", Map.of("message", Map.of("type", "string"))))
 			.build();
 
 		// Simulate incoming request
@@ -462,9 +462,9 @@ void testElicitationFailRequestHandling(McpSchema.ElicitResult.Action action) {
 		assertThat(asyncMcpClient.initialize().block()).isNotNull();
 
 		// Create a mock elicitation
-		var elicitRequest = McpSchema.ElicitRequest.builder()
-			.message("Test message")
-			.requestedSchema(Map.of("type", "object", "properties", Map.of("message", Map.of("type", "string"))))
+		var elicitRequest = McpSchema.ElicitRequest
+			.builder("Test message",
+					Map.of("type", "object", "properties", Map.of("message", Map.of("type", "string"))))
 			.build();
 
 		// Simulate incoming request
diff --git a/mcp-test/src/test/java/io/modelcontextprotocol/spec/McpSchemaTests.java b/mcp-test/src/test/java/io/modelcontextprotocol/spec/McpSchemaTests.java
index 09529f2e0..9cc9f1e11 100644
--- a/mcp-test/src/test/java/io/modelcontextprotocol/spec/McpSchemaTests.java
+++ b/mcp-test/src/test/java/io/modelcontextprotocol/spec/McpSchemaTests.java
@@ -133,13 +133,12 @@ void testCreateMessageRequestWithMeta() throws Exception {
 		Map<String, Object> meta = new HashMap<>();
 		meta.put("progressToken", "create-message-token-456");
 
-		McpSchema.CreateMessageRequest request = McpSchema.CreateMessageRequest.builder()
-			.messages(Collections.singletonList(message))
+		McpSchema.CreateMessageRequest request = McpSchema.CreateMessageRequest
+			.builder(Collections.singletonList(message), 1000)
 			.modelPreferences(preferences)
 			.systemPrompt("You are a helpful assistant")
 			.includeContext(McpSchema.CreateMessageRequest.ContextInclusionStrategy.THIS_SERVER)
 			.temperature(0.7)
-			.maxTokens(1000)
 			.stopSequences(Arrays.asList("STOP", "END"))
 			.metadata(metadata)
 			.meta(meta)
@@ -1363,13 +1362,12 @@ void testCreateMessageRequest() throws Exception {
 		Map<String, Object> metadata = new HashMap<>();
 		metadata.put("session", "test-session");
 
-		McpSchema.CreateMessageRequest request = McpSchema.CreateMessageRequest.builder()
-			.messages(Collections.singletonList(message))
+		McpSchema.CreateMessageRequest request = McpSchema.CreateMessageRequest
+			.builder(Collections.singletonList(message), 1000)
 			.modelPreferences(preferences)
 			.systemPrompt("You are a helpful assistant")
 			.includeContext(McpSchema.CreateMessageRequest.ContextInclusionStrategy.THIS_SERVER)
 			.temperature(0.7)
-			.maxTokens(1000)
 			.stopSequences(Arrays.asList("STOP", "END"))
 			.metadata(metadata)
 			.build();
@@ -1426,9 +1424,9 @@ void testCreateMessageResultUnknownStopReason() throws Exception {
 
 	@Test
 	void testCreateElicitationRequest() throws Exception {
-		McpSchema.ElicitRequest request = McpSchema.ElicitRequest.builder()
-			.requestedSchema(Map.of("type", "object", "required", List.of("a"), "properties",
-					Map.of("foo", Map.of("type", "string"))))
+		McpSchema.ElicitRequest request = McpSchema.ElicitRequest
+			.builder("Please provide additional information", Map.of("type", "object", "required", List.of("a"),
+					"properties", Map.of("foo", Map.of("type", "string"))))
 			.build();
 
 		String value = JSON_MAPPER.writeValueAsString(request);
@@ -1436,8 +1434,9 @@ void testCreateElicitationRequest() throws Exception {
 		assertThatJson(value).when(Option.IGNORING_ARRAY_ORDER)
 			.when(Option.IGNORING_EXTRA_ARRAY_ITEMS)
 			.isObject()
-			.isEqualTo(json("""
-					{"requestedSchema":{"properties":{"foo":{"type":"string"}},"required":["a"],"type":"object"}}"""));
+			.isEqualTo(
+					json("""
+							{"message":"Please provide additional information","requestedSchema":{"properties":{"foo":{"type":"string"}},"required":["a"],"type":"object"}}"""));
 	}
 
 	@Test
@@ -1464,9 +1463,7 @@ void testElicitRequestWithMeta() throws Exception {
 		Map<String, Object> meta = new HashMap<>();
 		meta.put("progressToken", "elicit-token-789");
 
-		McpSchema.ElicitRequest request = McpSchema.ElicitRequest.builder()
-			.message("Please provide your name")
-			.requestedSchema(requestedSchema)
+		McpSchema.ElicitRequest request = McpSchema.ElicitRequest.builder("Please provide your name", requestedSchema)
 			.meta(meta)
 			.build();