diff --git a/mcp-worker/src/axiosFetchDefaults.test.ts b/mcp-worker/src/axiosFetchDefaults.test.ts
new file mode 100644
index 00000000..6c2048de
--- /dev/null
+++ b/mcp-worker/src/axiosFetchDefaults.test.ts
@@ -0,0 +1,14 @@
+import { describe, expect, test } from 'vitest'
+import axios from 'axios'
+import { axiosClient } from '../../src/api/apiClient'
+import './axiosFetchDefaults'
+
+describe('axiosFetchDefaults', () => {
+    test('sets a Workers-compatible cache mode on global axios defaults', () => {
+        expect(axios.defaults.fetchOptions?.cache).toBe('no-store')
+    })
+
+    test('sets a Workers-compatible cache mode on the shared axiosClient', () => {
+        expect(axiosClient.defaults.fetchOptions?.cache).toBe('no-store')
+    })
+})
diff --git a/mcp-worker/src/axiosFetchDefaults.ts b/mcp-worker/src/axiosFetchDefaults.ts
new file mode 100644
index 00000000..5ef9b9c5
--- /dev/null
+++ b/mcp-worker/src/axiosFetchDefaults.ts
@@ -0,0 +1,13 @@
+import axios from 'axios'
+import { axiosClient } from '../../src/api/apiClient'
+
+/**
+ * axios >= 1.20 defaults fetch requests to `cache: 'default'`, which the
+ * Workers runtime rejects ("Unsupported cache mode: default"). Workers only
+ * accept `no-store` / `no-cache`, so set an explicit value on both the global
+ * axios defaults and the shared CLI client instance.
+ */
+const fetchOptions = { cache: 'no-store' as const }
+
+axios.defaults.fetchOptions = fetchOptions
+axiosClient.defaults.fetchOptions = fetchOptions
diff --git a/mcp-worker/src/index.ts b/mcp-worker/src/index.ts
index 736d5522..e8e12a2a 100644
--- a/mcp-worker/src/index.ts
+++ b/mcp-worker/src/index.ts
@@ -1,3 +1,4 @@
+import './axiosFetchDefaults'
 import OAuthProvider from '@cloudflare/workers-oauth-provider'
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
 import type { ToolAnnotations } from '@modelcontextprotocol/sdk/types.js'