diff --git a/packages/core/src/agents/agentLoader.test.ts b/packages/core/src/agents/agentLoader.test.ts
index ca2b2be78b..f80a1e8cb3 100644
--- a/packages/core/src/agents/agentLoader.test.ts
+++ b/packages/core/src/agents/agentLoader.test.ts
@@ -493,6 +493,42 @@ Body`);
       });
     });
 
+    it('should convert mcp_servers with auth block in local agent (google-credentials)', () => {
+      const markdown = {
+        kind: 'local' as const,
+        name: 'spanner-test-agent',
+        description: 'An agent to test Spanner MCP with auth',
+        mcp_servers: {
+          spanner: {
+            url: 'https://spanner.googleapis.com/mcp',
+            type: 'http' as const,
+            auth: {
+              type: 'google-credentials' as const,
+              scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+            },
+            timeout: 30000,
+          },
+        },
+        system_prompt: 'You are a Spanner test agent.',
+      };
+
+      const result = markdownToAgentDefinition(
+        markdown,
+      ) as LocalAgentDefinition;
+      expect(result.kind).toBe('local');
+      expect(result.mcpServers).toBeDefined();
+      expect(result.mcpServers!['spanner']).toMatchObject({
+        url: 'https://spanner.googleapis.com/mcp',
+        type: 'http',
+        authProviderType: 'google_credentials',
+        oauth: {
+          enabled: true,
+          scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+        },
+        timeout: 30000,
+      });
+    });
+
     it('should pass through unknown model names (e.g. auto)', () => {
       const markdown = {
         kind: 'local' as const,
diff --git a/packages/core/src/agents/agentLoader.ts b/packages/core/src/agents/agentLoader.ts
index d34d0e974e..4c5e771af9 100644
--- a/packages/core/src/agents/agentLoader.ts
+++ b/packages/core/src/agents/agentLoader.ts
@@ -17,7 +17,11 @@ import {
   DEFAULT_MAX_TIME_MINUTES,
 } from './types.js';
 import type { A2AAuthConfig } from './auth-provider/types.js';
-import { MCPServerConfig } from '../config/config.js';
+import {
+  MCPServerConfig,
+  AuthProviderType,
+  type MCPOAuthConfig,
+} from '../config/config.js';
 import { isValidToolName } from '../tools/tool-names.js';
 import { FRONTMATTER_REGEX } from '../skills/skillLoader.js';
 import { getErrorMessage } from '../utils/errors.js';
@@ -62,6 +66,22 @@ const mcpServerSchema = z.object({
   description: z.string().optional(),
   include_tools: z.array(z.string()).optional(),
   exclude_tools: z.array(z.string()).optional(),
+  auth: z
+    .union([
+      z.object({
+        type: z.literal('google-credentials'),
+        scopes: z.array(z.string()).optional(),
+      }),
+      z.object({
+        type: z.literal('oauth'),
+        client_id: z.string().optional(),
+        client_secret: z.string().optional(),
+        scopes: z.array(z.string()).optional(),
+        authorization_url: z.string().url().optional(),
+        token_url: z.string().url().optional(),
+      }),
+    ])
+    .optional(),
 });
 
 const localAgentSchema = z
@@ -74,9 +94,12 @@ const localAgentSchema = z
       .array(
         z
           .string()
-          .refine((val) => isValidToolName(val, { allowWildcards: true }), {
-            message: 'Invalid tool name',
-          }),
+          .refine(
+            (val: string) => isValidToolName(val, { allowWildcards: true }),
+            {
+              message: 'Invalid tool name',
+            },
+          ),
       )
       .optional(),
     mcp_servers: z.record(mcpServerSchema).optional(),
@@ -191,7 +214,7 @@ const remoteAgentJsonSchema = baseRemoteAgentSchema
   .extend({
     agent_card_url: z.undefined().optional(),
     agent_card_json: z.string().refine(
-      (val) => {
+      (val: string) => {
         try {
           JSON.parse(val);
           return true;
@@ -511,6 +534,28 @@ export function markdownToAgentDefinition(
   const mcpServers: Record<string, MCPServerConfig> = {};
   if (markdown.mcp_servers) {
     for (const [name, config] of Object.entries(markdown.mcp_servers)) {
+      let authProviderType: AuthProviderType | undefined = undefined;
+      let oauth: MCPOAuthConfig | undefined = undefined;
+
+      if (config.auth) {
+        if (config.auth.type === 'google-credentials') {
+          authProviderType = AuthProviderType.GOOGLE_CREDENTIALS;
+          oauth = {
+            enabled: true,
+            scopes: config.auth.scopes,
+          };
+        } else if (config.auth.type === 'oauth') {
+          oauth = {
+            enabled: true,
+            clientId: config.auth.client_id,
+            clientSecret: config.auth.client_secret,
+            scopes: config.auth.scopes,
+            authorizationUrl: config.auth.authorization_url,
+            tokenUrl: config.auth.token_url,
+          };
+        }
+      }
+
       mcpServers[name] = new MCPServerConfig(
         config.command,
         config.args,
@@ -526,6 +571,9 @@ export function markdownToAgentDefinition(
         config.description,
         config.include_tools,
         config.exclude_tools,
+        undefined, // extension
+        oauth,
+        authProviderType,
       );
     }
   }