diff --git a/google-analytics/server/lib/ga-client.ts b/google-analytics/server/lib/ga-client.ts
index 005335bf..e41c2517 100644
--- a/google-analytics/server/lib/ga-client.ts
+++ b/google-analytics/server/lib/ga-client.ts
@@ -5,6 +5,8 @@ const GA4_DATA_API = "https://analyticsdata.googleapis.com/v1beta";
 const GA4_ADMIN_API = "https://analyticsadmin.googleapis.com/v1beta";
 // Property annotations are v1alpha-only (not present in v1beta).
 const GA4_ADMIN_ALPHA_API = "https://analyticsadmin.googleapis.com/v1alpha";
+// runFunnelReport only exists on the Data API's v1alpha; the v1beta path 404s.
+const GA4_DATA_ALPHA_API = "https://analyticsdata.googleapis.com/v1alpha";
 
 // Hard limit on pagination loops to prevent runaway requests if GA4 returns a
 // repeated nextPageToken during a quota event or transient backend failure.
@@ -107,7 +109,7 @@ export class GaClient {
 
   async runFunnelReport(property: string, body: object): Promise<unknown> {
     const prop = normalizeProperty(property);
-    return this.request(`${GA4_DATA_API}/${prop}:runFunnelReport`, {
+    return this.request(`${GA4_DATA_ALPHA_API}/${prop}:runFunnelReport`, {
       method: "POST",
       body: JSON.stringify(body),
     });
diff --git a/google-workspace/README.md b/google-workspace/README.md
index 5a0ef506..dd7cbf1a 100644
--- a/google-workspace/README.md
+++ b/google-workspace/README.md
@@ -54,6 +54,16 @@ mesh client ──► google-workspace MCP ──► calendarmcp.googleapis.com/
 
 The OAuth flow is the standard `createGoogleOAuth` from `@decocms/mcps-shared` — PKCE with refresh-token rotation. The full union of scopes is sent at consent time, so a single approval covers every service.
 
+### The OAuth client must be marked "agentic"
+
+From **2026-11-11** Google's Workspace MCP servers reject OAuth clients that are not marked as agentic (`is_agentic`, Google Cloud Console → Credentials → the OAuth client). From **2026-11-12** the setting is permanent: changing it means a new client ID, and every user reconnects.
+
+- The client in use is `GOOGLE_WORKSPACE_CLIENT_ID` / `GOOGLE_WORKSPACE_CLIENT_SECRET` when set, else the shared `GOOGLE_CLIENT_ID` / `GOOGLE_CLIENT_SECRET`.
+- Google recommends a separate client when one client serves both agent and non-agent traffic. All MCPs in this repo are agent traffic, so marking the shared client is enough unless it is also used elsewhere (e.g. a human sign-in).
+- If the client is not marked, tool calls fail with an explicit "not marked as agentic" error instead of the generic 403 re-auth hint.
+
+The REST-based Google MCPs in this repo (`google-gmail`, `google-drive`, `google-analytics`, ...) call the REST APIs, not Google's MCP servers, so they keep working either way.
+
 ## Tool definitions are committed snapshots
 
 Tool names, descriptions, JSON schemas and PRM scopes for each backend live in `server/tools/generated/<service>.json`. These are committed to the repo for reproducible builds.
diff --git a/google-workspace/server/lib/mcp-proxy.test.ts b/google-workspace/server/lib/mcp-proxy.test.ts
new file mode 100644
index 00000000..8f5e6caa
--- /dev/null
+++ b/google-workspace/server/lib/mcp-proxy.test.ts
@@ -0,0 +1,16 @@
+import { expect, test } from "bun:test";
+import { notAgenticError } from "./mcp-proxy.ts";
+
+test("explains Google's not-agentic rejection instead of a re-auth hint", () => {
+  const err = notAgenticError(
+    "The client is not marked as an AI agent. See https://...",
+  );
+  expect(err?.message).toContain("not marked as agentic");
+  expect(err?.message).toContain("Re-authenticating will not help");
+});
+
+test("leaves ordinary errors alone", () => {
+  expect(
+    notAgenticError("Request had insufficient authentication scopes."),
+  ).toBeNull();
+});
diff --git a/google-workspace/server/lib/mcp-proxy.ts b/google-workspace/server/lib/mcp-proxy.ts
index 36f843bf..b42b7205 100644
--- a/google-workspace/server/lib/mcp-proxy.ts
+++ b/google-workspace/server/lib/mcp-proxy.ts
@@ -20,6 +20,21 @@ interface JsonRpcError {
 
 type JsonRpcResponse = JsonRpcSuccess | JsonRpcError;
 
+/**
+ * From 2026-11-11 Google's Workspace MCP servers only accept OAuth clients
+ * flagged "agentic" (is_agentic) in Google Cloud Console; the rejection says
+ * the client "is not marked as an AI agent". Re-authenticating cannot fix
+ * that, so it must not be reported as a missing scope.
+ */
+export function notAgenticError(text: string): Error | null {
+  if (!/agentic|ai agent/i.test(text)) return null;
+  return new Error(
+    `Google rejected this MCP's OAuth client because it is not marked as agentic (is_agentic). ` +
+      `Re-authenticating will not help: a Google Cloud admin must enable the agentic setting on the ` +
+      `OAuth client (GOOGLE_WORKSPACE_CLIENT_ID, or GOOGLE_CLIENT_ID if unset). Upstream: ${text}`,
+  );
+}
+
 export async function proxyMcpCall(
   backendUrl: string,
   toolName: string,
@@ -51,23 +66,32 @@ export async function proxyMcpCall(
 
   if (res.status === 403) {
     const text = await res.text();
-    throw new Error(
-      `Google ${backendUrl} returned 403 Forbidden. The token is missing the required scope. Re-authenticate to grant the new permission. Body: ${text}`,
+    throw (
+      notAgenticError(text) ??
+      new Error(
+        `Google ${backendUrl} returned 403 Forbidden. The token is missing the required scope. Re-authenticate to grant the new permission. Body: ${text}`,
+      )
     );
   }
 
   if (!res.ok) {
     const text = await res.text();
-    throw new Error(
-      `Google MCP backend error ${res.status} on ${toolName}: ${text}`,
+    throw (
+      notAgenticError(text) ??
+      new Error(
+        `Google MCP backend error ${res.status} on ${toolName}: ${text}`,
+      )
     );
   }
 
   const json = (await res.json()) as JsonRpcResponse;
 
   if ("error" in json) {
-    throw new Error(
-      `Google MCP JSON-RPC error on ${toolName}: ${json.error.message} (code ${json.error.code})`,
+    throw (
+      notAgenticError(json.error.message) ??
+      new Error(
+        `Google MCP JSON-RPC error on ${toolName}: ${json.error.message} (code ${json.error.code})`,
+      )
     );
   }
 
diff --git a/google-workspace/server/main.ts b/google-workspace/server/main.ts
index 961d3693..586417d3 100644
--- a/google-workspace/server/main.ts
+++ b/google-workspace/server/main.ts
@@ -17,7 +17,15 @@ const runtime = withRuntime<Env, typeof StateSchema, Registry>({
   },
   tools: (env: Env) => tools.map((createTool) => createTool(env)),
   prompts: () => prompts,
-  oauth: createGoogleOAuth({ scopes: GOOGLE_WORKSPACE_SCOPES }),
+  // Google's Workspace MCPs only accept OAuth clients marked "agentic". These
+  // optional vars let this MCP use its own agentic client instead of the
+  // GOOGLE_CLIENT_ID shared with the REST-based Google MCPs. Switching clients
+  // invalidates existing refresh tokens, so every user reconnects once.
+  oauth: createGoogleOAuth({
+    scopes: GOOGLE_WORKSPACE_SCOPES,
+    clientId: process.env.GOOGLE_WORKSPACE_CLIENT_ID || undefined,
+    clientSecret: process.env.GOOGLE_WORKSPACE_CLIENT_SECRET || undefined,
+  }),
 });
 
 serve(runtime.fetch);