@@ -529,7 +529,7 @@ private McpRequestHandler<CallToolResult> toolsCallRequestHandler() {
 
 			McpSchema.Tool tool = toolSpecification.get().tool();
 			CallToolResult validationError = ToolInputValidator.validate(tool, callToolRequest.arguments(),
-					this.validateToolInputs, this.jsonMapper, this.jsonSchemaValidator);
+					this.validateToolInputs, this.jsonSchemaValidator);
 			if (validationError != null) {
 				return Mono.just(validationError);
 			}
 
@@ -416,7 +416,7 @@ private McpStatelessRequestHandler<CallToolResult> toolsCallRequestHandler() {
 
 			McpSchema.Tool tool = toolSpecification.get().tool();
 			CallToolResult validationError = ToolInputValidator.validate(tool, callToolRequest.arguments(),
-					this.validateToolInputs, this.jsonMapper, this.jsonSchemaValidator);
+					this.validateToolInputs, this.jsonSchemaValidator);
 			if (validationError != null) {
 				return Mono.just(validationError);
 			}
 
@@ -7,8 +7,6 @@
 import java.util.List;
 import java.util.Map;
 
-import io.modelcontextprotocol.json.McpJsonMapper;
-import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
 import io.modelcontextprotocol.spec.McpSchema;
 import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
@@ -32,21 +30,17 @@ private ToolInputValidator() {
 	 * @param tool the tool definition containing the input schema
 	 * @param arguments the arguments to validate
 	 * @param validateToolInputs whether validation is enabled
-	 * @param jsonMapper the JSON mapper for schema conversion
 	 * @param validator the JSON schema validator (may be null)
 	 * @return CallToolResult with isError=true if validation fails, null if valid or
 	 * validation skipped
 	 */
 	public static CallToolResult validate(McpSchema.Tool tool, Map<String, Object> arguments,
-			boolean validateToolInputs, McpJsonMapper jsonMapper, JsonSchemaValidator validator) {
+			boolean validateToolInputs, JsonSchemaValidator validator) {
 		if (!validateToolInputs || tool.inputSchema() == null || validator == null) {
 			return null;
 		}
-		Map<String, Object> inputSchema = jsonMapper.convertValue(tool.inputSchema(),
-				new TypeRef<Map<String, Object>>() {
-				});
 		Map<String, Object> args = arguments != null ? arguments : Map.of();
-		var validation = validator.validate(inputSchema, args);
+		var validation = validator.validate(tool.inputSchema(), args);
 		if (!validation.valid()) {
 			logger.warn("Tool '{}' input validation failed: {}", tool.name(), validation.errorMessage());
 			return CallToolResult.builder()
 
@@ -7,11 +7,8 @@
 import java.util.List;
 import java.util.Map;
 
-import io.modelcontextprotocol.json.McpJsonMapper;
-import io.modelcontextprotocol.json.TypeRef;
 import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
 import io.modelcontextprotocol.json.schema.JsonSchemaValidator.ValidationResponse;
-import io.modelcontextprotocol.spec.McpSchema;
 import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
 import io.modelcontextprotocol.spec.McpSchema.TextContent;
 import io.modelcontextprotocol.spec.McpSchema.Tool;
@@ -26,15 +23,15 @@
 
 /**
  * Tests for {@link ToolInputValidator}.
+ *
+ * @author Andrei Shakirin
  */
 class ToolInputValidatorTests {
 
-	private final McpJsonMapper jsonMapper = mock(McpJsonMapper.class);
-
 	private final JsonSchemaValidator validator = mock(JsonSchemaValidator.class);
 
-	private final McpSchema.JsonSchema inputSchema = new McpSchema.JsonSchema("object",
-			Map.of("name", Map.of("type", "string")), List.of("name"), null, null, null);
+	private final Map<String, Object> inputSchema = Map.of("type", "object", "properties",
+			Map.of("name", Map.of("type", "string")), "required", List.of("name"));
 
 	private final Tool toolWithSchema = Tool.builder()
 		.name("test-tool")
@@ -46,62 +43,53 @@ class ToolInputValidatorTests {
 
 	@Test
 	void validate_whenDisabled_returnsNull() {
-		CallToolResult result = ToolInputValidator.validate(toolWithSchema, Map.of("name", "test"), false, jsonMapper,
-				validator);
+		CallToolResult result = ToolInputValidator.validate(toolWithSchema, Map.of("name", "test"), false, validator);
 
 		assertThat(result).isNull();
 		verify(validator, never()).validate(any(), any());
 	}
 
 	@Test
 	void validate_whenNoSchema_returnsNull() {
-		CallToolResult result = ToolInputValidator.validate(toolWithoutSchema, Map.of("name", "test"), true, jsonMapper,
-				validator);
+		CallToolResult result = ToolInputValidator.validate(toolWithoutSchema, Map.of("name", "test"), true, validator);
 
 		assertThat(result).isNull();
 		verify(validator, never()).validate(any(), any());
 	}
 
 	@Test
 	void validate_whenNoValidator_returnsNull() {
-		CallToolResult result = ToolInputValidator.validate(toolWithSchema, Map.of("name", "test"), true, jsonMapper,
-				null);
+		CallToolResult result = ToolInputValidator.validate(toolWithSchema, Map.of("name", "test"), true, null);
 
 		assertThat(result).isNull();
 	}
 
 	@Test
-	@SuppressWarnings("unchecked")
 	void validate_withValidInput_returnsNull() {
-		when(jsonMapper.convertValue(any(), any(TypeRef.class))).thenReturn(Map.of("type", "object"));
 		when(validator.validate(any(), any())).thenReturn(ValidationResponse.asValid(null));
 
-		CallToolResult result = ToolInputValidator.validate(toolWithSchema, Map.of("name", "test"), true, jsonMapper,
-				validator);
+		CallToolResult result = ToolInputValidator.validate(toolWithSchema, Map.of("name", "test"), true, validator);
 
 		assertThat(result).isNull();
 	}
 
 	@Test
-	@SuppressWarnings("unchecked")
 	void validate_withInvalidInput_returnsErrorResult() {
-		when(jsonMapper.convertValue(any(), any(TypeRef.class))).thenReturn(Map.of("type", "object"));
 		when(validator.validate(any(), any())).thenReturn(ValidationResponse.asInvalid("missing required: 'name'"));
 
-		CallToolResult result = ToolInputValidator.validate(toolWithSchema, Map.of(), true, jsonMapper, validator);
+		CallToolResult result = ToolInputValidator.validate(toolWithSchema, Map.of(), true, validator);
 
 		assertThat(result).isNotNull();
 		assertThat(result.isError()).isTrue();
 		assertThat(((TextContent) result.content().get(0)).text()).contains("missing required: 'name'");
+		verify(validator).validate(any(), any());
 	}
 
 	@Test
-	@SuppressWarnings("unchecked")
 	void validate_withNullArguments_usesEmptyMap() {
-		when(jsonMapper.convertValue(any(), any(TypeRef.class))).thenReturn(Map.of("type", "object"));
 		when(validator.validate(any(), any())).thenReturn(ValidationResponse.asValid(null));
 
-		CallToolResult result = ToolInputValidator.validate(toolWithSchema, null, true, jsonMapper, validator);
+		CallToolResult result = ToolInputValidator.validate(toolWithSchema, null, true, validator);
 
 		assertThat(result).isNull();
 		verify(validator).validate(any(), any());
Original file line number	Diff line number	Diff line change
`@@ -529,7 +529,7 @@ private McpRequestHandler<CallToolResult> toolsCallRequestHandler() {`
`529`	`529`
`530`	`530`	`McpSchema.Tool tool = toolSpecification.get().tool();`
`531`	`531`	`CallToolResult validationError = ToolInputValidator.validate(tool, callToolRequest.arguments(),`
`532`		`- this.validateToolInputs, this.jsonMapper, this.jsonSchemaValidator);`
	`532`	`+ this.validateToolInputs, this.jsonSchemaValidator);`
`533`	`533`	`if (validationError != null) {`
`534`	`534`	`return Mono.just(validationError);`
`535`	`535`	`}`
Original file line number	Diff line number	Diff line change
`@@ -416,7 +416,7 @@ private McpStatelessRequestHandler<CallToolResult> toolsCallRequestHandler() {`
`416`	`416`
`417`	`417`	`McpSchema.Tool tool = toolSpecification.get().tool();`
`418`	`418`	`CallToolResult validationError = ToolInputValidator.validate(tool, callToolRequest.arguments(),`
`419`		`- this.validateToolInputs, this.jsonMapper, this.jsonSchemaValidator);`
	`419`	`+ this.validateToolInputs, this.jsonSchemaValidator);`
`420`	`420`	`if (validationError != null) {`
`421`	`421`	`return Mono.just(validationError);`
`422`	`422`	`}`