diff --git a/apps/mcp/src/server/tools/annotations.ts b/apps/mcp/src/server/tools/annotations.ts
index fd2a81e3..fe77f2e1 100644
--- a/apps/mcp/src/server/tools/annotations.ts
+++ b/apps/mcp/src/server/tools/annotations.ts
@@ -12,3 +12,11 @@ export const MEMORY_TOOL_ANNOTATIONS = {
 	idempotentHint: false,
 	openWorldHint: false,
 } as const
+
+/** Non-destructive account/session mutations, e.g. switching the active space. */
+export const SETTINGS_TOOL_ANNOTATIONS = {
+	readOnlyHint: false,
+	destructiveHint: false,
+	idempotentHint: true,
+	openWorldHint: false,
+} as const
diff --git a/apps/mcp/src/server/tools/guided-save.ts b/apps/mcp/src/server/tools/guided-save.ts
index 97fc1dc9..8b17b226 100644
--- a/apps/mcp/src/server/tools/guided-save.ts
+++ b/apps/mcp/src/server/tools/guided-save.ts
@@ -2,6 +2,7 @@ import { z } from "zod"
 import type { ViewMessage } from "../../shared/types"
 import { appResultMeta, appToolMeta } from "../app-metadata"
 import { effectiveContainerTagAccess } from "../auth/rbac"
+import { READ_ONLY_TOOL_ANNOTATIONS } from "./annotations"
 import type { ToolDeps } from "./types"
 
 export function register(deps: ToolDeps) {
@@ -14,6 +15,7 @@ export function register(deps: ToolDeps) {
 				prefill: z.string().optional().describe("Optional content to prefill"),
 			}),
 			_meta: appToolMeta(),
+			annotations: READ_ONLY_TOOL_ANNOTATIONS,
 		},
 		async (args) => {
 			try {
diff --git a/apps/mcp/src/server/tools/select-space.ts b/apps/mcp/src/server/tools/select-space.ts
index 3f74cb62..827f8808 100644
--- a/apps/mcp/src/server/tools/select-space.ts
+++ b/apps/mcp/src/server/tools/select-space.ts
@@ -2,6 +2,7 @@ import { z } from "zod"
 import type { ViewMessage } from "../../shared/types"
 import { appResultMeta, appToolMeta } from "../app-metadata"
 import { effectiveContainerTagAccess } from "../auth/rbac"
+import { READ_ONLY_TOOL_ANNOTATIONS } from "./annotations"
 import type { ToolDeps } from "./types"
 
 export function register(deps: ToolDeps) {
@@ -13,6 +14,7 @@ export function register(deps: ToolDeps) {
 				"Choose the active Supermemory space. Shows available spaces as interactive cards.",
 			inputSchema: z.object({}),
 			_meta: appToolMeta(),
+			annotations: READ_ONLY_TOOL_ANNOTATIONS,
 		},
 		async () => {
 			try {
diff --git a/apps/mcp/src/server/tools/set-active-tag.ts b/apps/mcp/src/server/tools/set-active-tag.ts
index 3d93d57e..7797b460 100644
--- a/apps/mcp/src/server/tools/set-active-tag.ts
+++ b/apps/mcp/src/server/tools/set-active-tag.ts
@@ -2,6 +2,7 @@ import { z } from "zod"
 import type { ViewMessage } from "../../shared/types"
 import { appResultMeta, appToolMeta } from "../app-metadata"
 import { containerTagSchema } from "../container-tag"
+import { SETTINGS_TOOL_ANNOTATIONS } from "./annotations"
 import type { ToolDeps } from "./types"
 
 export function register(deps: ToolDeps) {
@@ -14,6 +15,7 @@ export function register(deps: ToolDeps) {
 				viewId: z.string().uuid().optional(),
 			}),
 			_meta: appToolMeta(["app"]),
+			annotations: SETTINGS_TOOL_ANNOTATIONS,
 		},
 		async (args) => {
 			const { containerTag } = args
diff --git a/apps/mcp/src/server/tools/upload-file.ts b/apps/mcp/src/server/tools/upload-file.ts
index 4a6c2f15..6b905cd3 100644
--- a/apps/mcp/src/server/tools/upload-file.ts
+++ b/apps/mcp/src/server/tools/upload-file.ts
@@ -2,6 +2,7 @@ import { z } from "zod"
 import type { ViewMessage } from "../../shared/types"
 import { appResultMeta, appToolMeta } from "../app-metadata"
 import { effectiveContainerTagAccess } from "../auth/rbac"
+import { READ_ONLY_TOOL_ANNOTATIONS } from "./annotations"
 import type { ToolDeps } from "./types"
 
 export function register(deps: ToolDeps) {
@@ -12,6 +13,7 @@ export function register(deps: ToolDeps) {
 			description: "Upload a file (PDF, text, image, video) to memory.",
 			inputSchema: z.object({}),
 			_meta: appToolMeta(),
+			annotations: READ_ONLY_TOOL_ANNOTATIONS,
 		},
 		async () => {
 			try {