build: validate duplicate MCP tool names before packaging

build.gradle

@@ -49,3 +49,20 @@ subprojects {
         useJUnitPlatform()
     }
 }
+
+def toolCoreProject = project(':dap-tool-core')
+
+tasks.register('validateMcpToolNames', JavaExec) {
+    group = 'verification'
+    description = 'Checks duplicate @McpFunction names across all Tool modules before packaging.'
+    dependsOn toolCoreProject.tasks.named('classes')
+    classpath = toolCoreProject.sourceSets.main.runtimeClasspath
+    mainClass.set('io.shinhanlife.dap.lib.validation.McpToolNameValidationRunner')
+    args rootProject.projectDir.absolutePath
+}
+
+subprojects {
+    tasks.matching { it.name == 'bootJar' }.configureEach {
+        dependsOn rootProject.tasks.named('validateMcpToolNames')
+    }
+}

dap-tool-core/src/main/java/io/shinhanlife/dap/lib/validation/McpToolNameValidationRunner.java

@@ -0,0 +1,21 @@
+package io.shinhanlife.dap.lib.validation;
+
+import java.nio.file.Path;
+
+/** Gradle entry point for validating unique MCP Tool names before packaging. */
+public final class McpToolNameValidationRunner {
+
+    private McpToolNameValidationRunner() {
+    }
+
+    public static void main(String[] args) {
+        if (args.length != 1) {
+            throw new IllegalArgumentException("Usage: McpToolNameValidationRunner <project-root>");
+        }
+        validate(Path.of(args[0]));
+    }
+
+    static void validate(Path projectRoot) {
+        McpToolNameValidator.assertUnique(projectRoot);
+    }
+}

dap-tool-core/src/test/java/io/shinhanlife/dap/lib/validation/McpToolNameValidatorTest.java

@@ -42,6 +42,15 @@ class McpToolNameValidatorTest {
         assertTrue(exception.getMessage().contains("dap-tool-second"));
     }
 
+    @Test
+    void validationRunnerRejectsDuplicateMcpFunctionNamesBeforePackaging() throws IOException {
+        writeToolSource("dap-tool-first", "FirstTool.java", "first", "send_sms");
+        writeToolSource("dap-tool-second", "SecondTool.java", "second", "send_sms");
+
+        assertThrows(IllegalStateException.class,
+                () -> McpToolNameValidationRunner.validate(temporaryRoot));
+    }
+
     @Test
     void acceptsCurrentProjectToolNames() {
         assertDoesNotThrow(() -> McpToolNameValidator.assertUnique(findProjectRoot()));