diff --git a/dap-was-cus/src/main/resources/application.yml b/dap-was-cus/src/main/resources/application.yml
index dfc56afed..ed740b986 100644
--- a/dap-was-cus/src/main/resources/application.yml
+++ b/dap-was-cus/src/main/resources/application.yml
@@ -15,5 +15,6 @@ mcp:
     # Set the AA-assigned prefix before MCP pull activation (for example: cus.).
     name-prefix: ""
   security:
+    api-key: ${TOOL_SERVER_API_KEY:tool-server-key}
     tenant-domains:
       TESTER-DEV: ALL
diff --git a/dap-was-lib/src/main/java/io/shinhanlife/dap/lib/mcp/security/ApiKeyInterceptor.java b/dap-was-lib/src/main/java/io/shinhanlife/dap/lib/mcp/security/ApiKeyInterceptor.java
index de2b65280..28ea41e03 100644
--- a/dap-was-lib/src/main/java/io/shinhanlife/dap/lib/mcp/security/ApiKeyInterceptor.java
+++ b/dap-was-lib/src/main/java/io/shinhanlife/dap/lib/mcp/security/ApiKeyInterceptor.java
@@ -40,25 +40,30 @@ public class ApiKeyInterceptor implements HandlerInterceptor {
         }
 
         String apiKey = request.getHeader("X-Tool-Server-API-Key");
+        String configuredApiKey = securityProperties.getApiKey();
         Map<String, String> validApiKeys = securityProperties.getApiKeys();
+        boolean singleApiKeyConfigured = configuredApiKey != null && !configuredApiKey.isBlank();
+        boolean multipleApiKeysConfigured = validApiKeys != null && !validApiKeys.isEmpty();
 
         // 2. 만약 프로퍼티에 API Key가 하나도 설정되어 있지 않다면 (개발/로컬 환경 등) 인증 없이 통과시킵니다.
-        if (validApiKeys == null || validApiKeys.isEmpty()) {
+        if (!singleApiKeyConfigured && !multipleApiKeysConfigured) {
             MDC.put("tenantId", "anonymous");
             request.setAttribute("tenantId", "anonymous");
             log.debug(" [보안 패스] 등록된 API Key 없음 - 익명 사용자(anonymous)로 통과");
             return true;
         }
 
-        // 3. 헤더로 들어온 API Key가 우리가 발급해준 목록(Map)에 존재하는지 확인합니다.
-        if (apiKey == null || !validApiKeys.containsKey(apiKey)) {
+        // 3. 헤더로 들어온 API Key가 단일 공통 Key 또는 다중 테넌트 Key 목록에 존재하는지 확인합니다.
+        boolean matchesSingleApiKey = singleApiKeyConfigured && configuredApiKey.equals(apiKey);
+        boolean matchesMultipleApiKeys = apiKey != null && multipleApiKeysConfigured && validApiKeys.containsKey(apiKey);
+        if (!matchesSingleApiKey && !matchesMultipleApiKeys) {
             log.warn(" [보안 차단] 유효하지 않은 API Key 접근 시도 - IP: {}", request.getRemoteAddr());
             response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Invalid API Key");
             return false; // 컨트롤러로 넘어가지 않음
         }
 
         // 4. 유효하다면 해당 키에 맵핑된 Tenant ID(식별자)를 가져옵니다. (ex. mcp-client-1)
-        String tenantId = validApiKeys.get(apiKey);
+        String tenantId = matchesSingleApiKey ? "dapms" : validApiKeys.get(apiKey);
 
         // 4. 추출한 Tenant ID를 현재 스레드의 로깅 컨텍스트(MDC)에 저장합니다.
         // 이렇게 하면 이 요청이 끝날 때까지 찍히는 모든 로그에 어떤 테넌트가 호출했는지 자동으로 기록됩니다.
diff --git a/dap-was-lib/src/main/java/io/shinhanlife/dap/lib/mcp/security/SecurityProperties.java b/dap-was-lib/src/main/java/io/shinhanlife/dap/lib/mcp/security/SecurityProperties.java
index 381164e61..e69e6f034 100644
--- a/dap-was-lib/src/main/java/io/shinhanlife/dap/lib/mcp/security/SecurityProperties.java
+++ b/dap-was-lib/src/main/java/io/shinhanlife/dap/lib/mcp/security/SecurityProperties.java
@@ -31,6 +31,9 @@ import java.util.Map;
 @Component
 @ConfigurationProperties(prefix = "mcp.security")
 public class SecurityProperties {
+    // DAPMS가 X-Tool-Server-API-Key 헤더로 전달하는 단일 공통 Key
+    private String apiKey;
+
     // API Key를 Key로, Tenant ID를 Value로 가지는 맵 
     private Map<String, String> apiKeys = new HashMap<>();
 
diff --git a/dap-was-lib/src/test/java/io/shinhanlife/dap/lib/mcp/security/ApiKeyInterceptorTest.java b/dap-was-lib/src/test/java/io/shinhanlife/dap/lib/mcp/security/ApiKeyInterceptorTest.java
index d0ca486a4..42cc9cf1e 100644
--- a/dap-was-lib/src/test/java/io/shinhanlife/dap/lib/mcp/security/ApiKeyInterceptorTest.java
+++ b/dap-was-lib/src/test/java/io/shinhanlife/dap/lib/mcp/security/ApiKeyInterceptorTest.java
@@ -4,6 +4,9 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 import java.util.Map;
 import org.junit.jupiter.api.Test;
+import org.springframework.boot.context.properties.bind.Bindable;
+import org.springframework.boot.context.properties.bind.Binder;
+import org.springframework.boot.context.properties.source.MapConfigurationPropertySource;
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
 
@@ -23,4 +26,40 @@ class ApiKeyInterceptorTest {
         assertThat(allowed).isTrue();
         assertThat(request.getAttribute("tenantId")).isEqualTo("dapms");
     }
+
+    @Test
+    void rejectsARequestWhenItDoesNotMatchTheConfiguredSingleApiKey() throws Exception {
+        SecurityProperties properties = bindSingleApiKey("tool-server-key");
+        ApiKeyInterceptor interceptor = new ApiKeyInterceptor(properties);
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        request.addHeader("X-Tool-Server-API-Key", "wrong-key");
+        MockHttpServletResponse response = new MockHttpServletResponse();
+
+        boolean allowed = interceptor.preHandle(request, response, new Object());
+
+        assertThat(allowed).isFalse();
+        assertThat(response.getStatus()).isEqualTo(401);
+    }
+
+    @Test
+    void authenticatesARequestWithTheConfiguredSingleApiKey() throws Exception {
+        SecurityProperties properties = bindSingleApiKey("tool-server-key");
+        ApiKeyInterceptor interceptor = new ApiKeyInterceptor(properties);
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        request.addHeader("X-Tool-Server-API-Key", "tool-server-key");
+        MockHttpServletResponse response = new MockHttpServletResponse();
+
+        boolean allowed = interceptor.preHandle(request, response, new Object());
+
+        assertThat(allowed).isTrue();
+        assertThat(request.getAttribute("tenantId")).isEqualTo("dapms");
+    }
+
+    private SecurityProperties bindSingleApiKey(String apiKey) {
+        SecurityProperties properties = new SecurityProperties();
+        Binder binder = new Binder(new MapConfigurationPropertySource(
+                Map.of("mcp.security.api-key", apiKey)));
+        binder.bind("mcp.security", Bindable.ofInstance(properties));
+        return properties;
+    }
 }
diff --git a/dap-was-pro/src/main/resources/application.yml b/dap-was-pro/src/main/resources/application.yml
index 8838ee170..4054bcc1c 100644
--- a/dap-was-pro/src/main/resources/application.yml
+++ b/dap-was-pro/src/main/resources/application.yml
@@ -14,5 +14,6 @@ mcp:
     bundle-id: was-pro
     name-prefix: ""
   security:
+    api-key: ${TOOL_SERVER_API_KEY:tool-server-key}
     tenant-domains:
       TESTER-DEV: ALL
diff --git a/dap-was-sal/src/main/resources/application.yml b/dap-was-sal/src/main/resources/application.yml
index 964b96532..e26a45e7c 100644
--- a/dap-was-sal/src/main/resources/application.yml
+++ b/dap-was-sal/src/main/resources/application.yml
@@ -15,5 +15,6 @@ mcp:
     # Set the AA-assigned prefix before MCP pull activation (for example: sal.).
     name-prefix: ""
   security:
+    api-key: ${TOOL_SERVER_API_KEY:tool-server-key}
     tenant-domains:
       TESTER-DEV: ALL
diff --git a/dap-was-sys/src/main/resources/application.yml b/dap-was-sys/src/main/resources/application.yml
index 5c05991ba..5b1001f06 100644
--- a/dap-was-sys/src/main/resources/application.yml
+++ b/dap-was-sys/src/main/resources/application.yml
@@ -14,5 +14,6 @@ mcp:
     bundle-id: was-sys
     name-prefix: ""
   security:
+    api-key: ${TOOL_SERVER_API_KEY:tool-server-key}
     tenant-domains:
       TESTER-DEV: ALL