Merge pull request modelcontextprotocol#294 from matteo8p/create-helper-functions-tool-visibility

Add `isToolVisibilityModelOnly` and `isToolVisibilityAppOnly` helper functions

Author: antonpk1

src/app-bridge.test.ts

@@ -17,6 +17,8 @@ import { App } from "./app";
 import {
   AppBridge,
   getToolUiResourceUri,
+  isToolVisibilityModelOnly,
+  isToolVisibilityAppOnly,
   type McpUiHostCapabilities,
 } from "./app-bridge";
 
@@ -921,3 +923,153 @@ describe("getToolUiResourceUri", () => {
     });
   });
 });
+
+describe("isToolVisibilityModelOnly", () => {
+  describe("returns true", () => {
+    it("when visibility is exactly ['model']", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: ["model"] } },
+      };
+      expect(isToolVisibilityModelOnly(tool)).toBe(true);
+    });
+  });
+
+  describe("returns false", () => {
+    it("when visibility is ['app']", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: ["app"] } },
+      };
+      expect(isToolVisibilityModelOnly(tool)).toBe(false);
+    });
+
+    it("when visibility is ['model', 'app']", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: ["model", "app"] } },
+      };
+      expect(isToolVisibilityModelOnly(tool)).toBe(false);
+    });
+
+    it("when visibility is ['app', 'model']", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: ["app", "model"] } },
+      };
+      expect(isToolVisibilityModelOnly(tool)).toBe(false);
+    });
+
+    it("when visibility is empty array", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: [] } },
+      };
+      expect(isToolVisibilityModelOnly(tool)).toBe(false);
+    });
+
+    it("when visibility is undefined", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: {} },
+      };
+      expect(isToolVisibilityModelOnly(tool)).toBe(false);
+    });
+
+    it("when _meta.ui is missing", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: {},
+      };
+      expect(isToolVisibilityModelOnly(tool)).toBe(false);
+    });
+
+    it("when _meta is missing", () => {
+      const tool = { name: "test-tool" };
+      expect(isToolVisibilityModelOnly(tool)).toBe(false);
+    });
+
+    it("when tool has resourceUri but no visibility", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { resourceUri: "ui://server/app.html" } },
+      };
+      expect(isToolVisibilityModelOnly(tool)).toBe(false);
+    });
+  });
+});
+
+describe("isToolVisibilityAppOnly", () => {
+  describe("returns true", () => {
+    it("when visibility is exactly ['app']", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: ["app"] } },
+      };
+      expect(isToolVisibilityAppOnly(tool)).toBe(true);
+    });
+  });
+
+  describe("returns false", () => {
+    it("when visibility is ['model']", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: ["model"] } },
+      };
+      expect(isToolVisibilityAppOnly(tool)).toBe(false);
+    });
+
+    it("when visibility is ['model', 'app']", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: ["model", "app"] } },
+      };
+      expect(isToolVisibilityAppOnly(tool)).toBe(false);
+    });
+
+    it("when visibility is ['app', 'model']", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: ["app", "model"] } },
+      };
+      expect(isToolVisibilityAppOnly(tool)).toBe(false);
+    });
+
+    it("when visibility is empty array", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { visibility: [] } },
+      };
+      expect(isToolVisibilityAppOnly(tool)).toBe(false);
+    });
+
+    it("when visibility is undefined", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: {} },
+      };
+      expect(isToolVisibilityAppOnly(tool)).toBe(false);
+    });
+
+    it("when _meta.ui is missing", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: {},
+      };
+      expect(isToolVisibilityAppOnly(tool)).toBe(false);
+    });
+
+    it("when _meta is missing", () => {
+      const tool = { name: "test-tool" };
+      expect(isToolVisibilityAppOnly(tool)).toBe(false);
+    });
+
+    it("when tool has resourceUri but no visibility", () => {
+      const tool = {
+        name: "test-tool",
+        _meta: { ui: { resourceUri: "ui://server/app.html" } },
+      };
+      expect(isToolVisibilityAppOnly(tool)).toBe(false);
+    });
+  });
+});

src/app-bridge.ts

@@ -78,6 +78,7 @@ import {
   McpUiRequestDisplayModeRequestSchema,
   McpUiRequestDisplayModeResult,
   McpUiResourcePermissions,
+  McpUiToolMeta,
 } from "./types";
 export * from "./types";
 export { RESOURCE_URI_META_KEY, RESOURCE_MIME_TYPE } from "./app";
@@ -110,7 +111,7 @@ export { PostMessageTransport } from "./message-transport";
  */
 export function getToolUiResourceUri(tool: Partial<Tool>): string | undefined {
   // Try new nested format first: _meta.ui.resourceUri
-  const uiMeta = tool._meta?.ui as { resourceUri?: unknown } | undefined;
+  const uiMeta = tool._meta?.ui as McpUiToolMeta | undefined;
   let uri: unknown = uiMeta?.resourceUri;
 
   // Fall back to deprecated flat format: _meta["ui/resourceUri"]
@@ -126,6 +127,34 @@ export function getToolUiResourceUri(tool: Partial<Tool>): string | undefined {
   return undefined;
 }
 
+/**
+ * Check if a tool is visible to the model only.
+ *
+ * @param tool - Tool object with visibility metadata
+ * @returns True if the tool is visible to the model only, false otherwise
+ */
+export function isToolVisibilityModelOnly(tool: Partial<Tool>): boolean {
+  const uiMeta = tool._meta?.ui as McpUiToolMeta | undefined;
+  const visibility = uiMeta?.visibility as Array<"model" | "app"> | undefined;
+  if (!visibility) return false;
+  if (visibility.length === 1 && visibility[0] === "model") return true;
+  return false;
+}
+
+/**
+ * Check if a tool is visible to the app only.
+ *
+ * @param tool - Tool object with visibility metadata
+ * @returns True if the tool is visible to the app only, false otherwise
+ */
+export function isToolVisibilityAppOnly(tool: Partial<Tool>): boolean {
+  const uiMeta = tool._meta?.ui as McpUiToolMeta | undefined;
+  const visibility = uiMeta?.visibility as Array<"model" | "app"> | undefined;
+  if (!visibility) return false;
+  if (visibility.length === 1 && visibility[0] === "app") return true;
+  return false;
+}
+
 /**
  * Build iframe `allow` attribute string from permissions.
  *