diff --git a/docs/cloudflare/oauth-architecture.md b/docs/cloudflare/oauth-architecture.md
index bf05b71a7..a52da228f 100644
--- a/docs/cloudflare/oauth-architecture.md
+++ b/docs/cloudflare/oauth-architecture.md
@@ -243,6 +243,7 @@ interface WorkerProps {
   scope: string; // MCP permissions granted
   grantedSkills?: string[]; // Skills granted (primary authorization)
   // grantedScopes is deprecated and will be removed Jan 1, 2026
+  upstreamScopes?: string[]; // Scopes Sentry granted on the upstream token
 }
 ```
 
diff --git a/docs/operations/security.md b/docs/operations/security.md
index 4ff6e78c2..670ce6120 100644
--- a/docs/operations/security.md
+++ b/docs/operations/security.md
@@ -104,6 +104,10 @@ Today, runtime authorization for remote HTTP sessions is driven primarily by:
 
 `grantedScopes` still exists on tokens for backward compatibility with older
 clients, but it is transitional. Skills are the primary authorization model.
+Note that `grantedScopes` is derived from the selected skills, not from what
+Sentry granted. The scopes Sentry actually granted on the upstream token (from
+the `scope` field of Sentry's token response) are stored separately as
+`upstreamScopes`. Grants created before `upstreamScopes` existed do not have it.
 
 Direct `Sentry-Bearer` sessions default to all active skills and can be narrowed
 with `skills` or `disable-skills` query parameters. They do not get OAuth
diff --git a/packages/mcp-cloudflare/src/server/oauth/callback.test.ts b/packages/mcp-cloudflare/src/server/oauth/callback.test.ts
index dd69a614a..9f2fec656 100644
--- a/packages/mcp-cloudflare/src/server/oauth/callback.test.ts
+++ b/packages/mcp-cloudflare/src/server/oauth/callback.test.ts
@@ -664,6 +664,82 @@ describe("oauth callback routes", () => {
       expect(body.result?.protocolVersion).toBeDefined();
     });
 
+    it("stores the scopes Sentry actually granted alongside skill-derived grantedScopes", async () => {
+      // Sentry returns the token's real scopes in the token response. With
+      // only `inspect` selected, skill-derived grantedScopes are read-only,
+      // but the upstream token can still carry write scopes.
+      exchangeCodeForAccessToken.mockResolvedValueOnce([
+        {
+          access_token: "sentry-access-token",
+          refresh_token: "sentry-refresh-token",
+          expires_in: 3600,
+          expires_at: new Date(Date.now() + 3600_000).toISOString(),
+          token_type: "bearer",
+          user: { id: "user-123", name: "Test User" },
+          scope: "team:write org:read event:write  project:write alerts:write",
+        },
+        null,
+      ]);
+
+      const testEnv = createTestEnv();
+      const completeAuthorization = vi.spyOn(
+        testEnv.OAUTH_PROVIDER,
+        "completeAuthorization",
+      );
+      const oauthApp = createTestApp();
+      const client = await createClient(testEnv);
+      const cookie = await approveClient(oauthApp, testEnv, client.clientId);
+      const state = await createSignedCallbackState(client.clientId);
+
+      const callbackResponse = await callCallback(oauthApp, testEnv, {
+        state,
+        code: "test-code",
+        cookie,
+      });
+
+      expect(callbackResponse.status).toBe(302);
+      expect(completeAuthorization).toHaveBeenCalledOnce();
+      const props = completeAuthorization.mock.calls[0]![0].props as Record<
+        string,
+        unknown
+      >;
+
+      expect(props.upstreamScopes).toEqual([
+        "alerts:write",
+        "event:write",
+        "org:read",
+        "project:write",
+        "team:write",
+      ]);
+      expect(props.grantedSkills).toEqual(["inspect"]);
+      expect(props.grantedScopes).not.toEqual(props.upstreamScopes);
+    });
+
+    it("omits upstreamScopes when Sentry's token response has no scope", async () => {
+      const testEnv = createTestEnv();
+      const completeAuthorization = vi.spyOn(
+        testEnv.OAUTH_PROVIDER,
+        "completeAuthorization",
+      );
+      const oauthApp = createTestApp();
+      const client = await createClient(testEnv);
+      const cookie = await approveClient(oauthApp, testEnv, client.clientId);
+      const state = await createSignedCallbackState(client.clientId);
+
+      const callbackResponse = await callCallback(oauthApp, testEnv, {
+        state,
+        code: "test-code",
+        cookie,
+      });
+
+      expect(callbackResponse.status).toBe(302);
+      const props = completeAuthorization.mock.calls[0]![0].props as Record<
+        string,
+        unknown
+      >;
+      expect(props.upstreamScopes).toBeUndefined();
+    });
+
     it("completes callback for a scoped resource, exchanges the code, and uses the token at the same scoped /mcp path", async () => {
       const scopedResource =
         "http://localhost/mcp/sentry-mcp-evals/cloudflare-mcp";
diff --git a/packages/mcp-cloudflare/src/server/oauth/helpers.ts b/packages/mcp-cloudflare/src/server/oauth/helpers.ts
index 41e3e85b2..c75ef446e 100644
--- a/packages/mcp-cloudflare/src/server/oauth/helpers.ts
+++ b/packages/mcp-cloudflare/src/server/oauth/helpers.ts
@@ -588,6 +588,7 @@ export async function tokenExchangeCallback(
     clientId: rawProps.clientId as string,
     scope: rawProps.scope as string,
     grantedScopes: rawProps.grantedScopes,
+    upstreamScopes: rawProps.upstreamScopes,
     grantedSkills: rawProps.grantedSkills,
   } satisfies WorkerProps & Record<string, unknown>;
 
diff --git a/packages/mcp-cloudflare/src/server/oauth/routes/callback.ts b/packages/mcp-cloudflare/src/server/oauth/routes/callback.ts
index 806af7539..0a7698769 100644
--- a/packages/mcp-cloudflare/src/server/oauth/routes/callback.ts
+++ b/packages/mcp-cloudflare/src/server/oauth/routes/callback.ts
@@ -42,6 +42,18 @@ function getUpstreamTokenExpiryTimestamp(payload: {
     : Date.now() + payload.expires_in * 1000;
 }
 
+/**
+ * Parse the space-delimited `scope` from Sentry's token response (RFC 6749
+ * §5.1) into a sorted list. Returns undefined when Sentry omitted it so we
+ * don't record an empty list that looks like "no scopes granted".
+ */
+function parseUpstreamScopes(scope: string | undefined): string[] | undefined {
+  if (typeof scope !== "string") {
+    return undefined;
+  }
+  return Array.from(new Set(scope.split(/\s+/).filter(Boolean))).sort();
+}
+
 function getUpstreamUserLabel(payload: {
   user: { name: string | null; email?: string | null; id: string };
 }): string {
@@ -323,6 +335,9 @@ export default new Hono<{ Bindings: Env }>().get("/", async (c) => {
       // Scopes derived from skills - for backward compatibility with old MCP clients
       // that don't support grantedSkills and only understand grantedScopes
       grantedScopes: Array.from(grantedScopes),
+      // Scopes Sentry actually granted on the upstream token (from the token
+      // response), which can differ from the skill-derived grantedScopes
+      upstreamScopes: parseUpstreamScopes(payload.scope),
       grantedSkills, // Primary authorization method
 
       constraintOrganizationSlug,
diff --git a/packages/mcp-cloudflare/src/server/types.ts b/packages/mcp-cloudflare/src/server/types.ts
index 2a91d6816..5d493089e 100644
--- a/packages/mcp-cloudflare/src/server/types.ts
+++ b/packages/mcp-cloudflare/src/server/types.ts
@@ -30,6 +30,14 @@ export type WorkerProps = {
    * This field exists only for backward compatibility during the transition period.
    */
   grantedScopes?: string[];
+  /**
+   * Scopes Sentry actually granted on the upstream access token, as returned
+   * in the `scope` field of Sentry's OAuth token response. Unlike
+   * `grantedScopes` (derived from selected skills), this reflects what the
+   * stored Sentry token can really do. Absent on grants created before this
+   * field existed.
+   */
+  upstreamScopes?: string[];
   /** Primary authorization method - array of skill strings */
   grantedSkills?: string[];