feat: validate MCP tool input constraints

dap-tool-core/src/main/java/io/shinhanlife/dap/lib/annotation/McpValidation.java

@@ -0,0 +1,30 @@
+package io.shinhanlife.dap.lib.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * @package io.shinhanlife.dap.lib.annotation
+ * @className McpValidation
+ * @description Declares JSON Schema validation constraints for MCP tool input fields
+ * @author 0986406
+ * @create 2026.07.27
+ * <pre>
+ * ---------- revision history ----------
+ * date       author    description
+ * ---------- --------- ---------------------------
+ * 2026.07.27 0986406    initial creation
+ * </pre>
+ */
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface McpValidation {
+    boolean required() default false;
+    String pattern() default "";
+    long minimum() default Long.MIN_VALUE;
+    String[] allowedValues() default {};
+}

dap-tool-core/src/main/java/io/shinhanlife/dap/lib/util/JsonSchemaGenerator.java

@@ -3,6 +3,7 @@ package io.shinhanlife.dap.lib.util;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonPropertyDescription;
 import io.shinhanlife.dap.lib.annotation.McpParameter;
+import io.shinhanlife.dap.lib.annotation.McpValidation;
 import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -58,6 +59,20 @@ public class JsonSchemaGenerator {
             if ((jsonProp != null && jsonProp.required()) || (paramAnnotation != null && paramAnnotation.required())) {
                 requiredList.add(field.getName());
             }
+
+            McpValidation validation = field.getAnnotation(McpValidation.class);
+            if (validation != null && validation.required() && !requiredList.contains(field.getName())) {
+                requiredList.add(field.getName());
+            }
+            if (validation != null && !validation.pattern().isEmpty()) {
+                fieldSchema.put("pattern", validation.pattern());
+            }
+            if (validation != null && validation.minimum() != Long.MIN_VALUE) {
+                fieldSchema.put("minimum", validation.minimum());
+            }
+            if (validation != null && validation.allowedValues().length > 0) {
+                fieldSchema.put("enum", List.of(validation.allowedValues()));
+            }
             
             properties.put(field.getName(), fieldSchema);
         }

dap-tool-core/src/test/java/io/shinhanlife/dap/lib/util/JsonSchemaGeneratorTest.java

@@ -0,0 +1,57 @@
+package io.shinhanlife.dap.lib.util;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import io.shinhanlife.dap.lib.annotation.McpParameter;
+import io.shinhanlife.dap.lib.annotation.McpValidation;
+import java.util.List;
+import java.util.Map;
+import org.junit.jupiter.api.Test;
+
+/**
+ * @package io.shinhanlife.dap.lib.util
+ * @className JsonSchemaGeneratorTest
+ * @description JSON Schema constraint generation test
+ * @author 0986406
+ * @create 2026.07.27
+ * <pre>
+ * ---------- revision history ----------
+ * date       author    description
+ * ---------- --------- ---------------------------
+ * 2026.07.27 0986406    initial creation
+ * </pre>
+ */
+class JsonSchemaGeneratorTest {
+
+    @Test
+    void includesMcpParameterConstraintsInGeneratedSchema() {
+        Map<String, Object> schema = JsonSchemaGenerator.generateSchema(ValidatedRequest.class);
+        Map<String, Map<String, Object>> properties = properties(schema);
+
+        assertTrue(((List<String>) schema.get("required")).contains("phoneNumber"));
+        assertTrue(((List<String>) schema.get("required")).contains("approvalStatus"));
+        assertEquals("^01[0-9]{8,9}$", properties.get("phoneNumber").get("pattern"));
+        assertEquals(1L, properties.get("amount").get("minimum"));
+        assertEquals(List.of("APPROVE", "REJECT"), properties.get("approvalStatus").get("enum"));
+    }
+
+    @SuppressWarnings("unchecked")
+    private Map<String, Map<String, Object>> properties(Map<String, Object> schema) {
+        return (Map<String, Map<String, Object>>) schema.get("properties");
+    }
+
+    private static class ValidatedRequest {
+        @McpParameter(description = "recipient phone number", required = true)
+        @McpValidation(pattern = "^01[0-9]{8,9}$")
+        private String phoneNumber;
+
+        @McpParameter(description = "issue amount", required = true)
+        @McpValidation(minimum = 1)
+        private Long amount;
+
+        @McpParameter(description = "approval result")
+        @McpValidation(required = true, allowedValues = {"APPROVE", "REJECT"})
+        private String approvalStatus;
+    }
+}