diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 81f776ab..1824ee5a 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -15,8 +15,9 @@ We welcome contributions to the MCP Apps SDK! This document outlines the process
 1. Create a new branch for your changes
 2. Make your changes
 3. Run `npm run prettier` to ensure code style compliance
-4. Run `npm test` to verify all tests pass
-5. Submit a pull request
+4. If running prettier fails, run `npm run prettier:fix` to fix
+5. Run `npm test` to verify all tests pass
+6. Submit a pull request
 
 ## Pull Request Guidelines
 
diff --git a/src/app-bridge.test.ts b/src/app-bridge.test.ts
index 66d5f830..89c5458a 100644
--- a/src/app-bridge.test.ts
+++ b/src/app-bridge.test.ts
@@ -844,16 +844,6 @@ describe("getToolUiResourceUri", () => {
     });
   });
 
-  describe("deprecated flat format (_meta['ui/resourceUri'])", () => {
-    it("extracts resourceUri from deprecated format", () => {
-      const tool = {
-        name: "test-tool",
-        _meta: { "ui/resourceUri": "ui://server/app.html" },
-      };
-      expect(getToolUiResourceUri(tool)).toBe("ui://server/app.html");
-    });
-  });
-
   describe("format precedence", () => {
     it("prefers new nested format over deprecated format", () => {
       const tool = {
diff --git a/src/app-bridge.ts b/src/app-bridge.ts
index 079dc705..62fad9ae 100644
--- a/src/app-bridge.ts
+++ b/src/app-bridge.ts
@@ -80,7 +80,6 @@ import {
 } from "./types";
 export * from "./types";
 export { RESOURCE_URI_META_KEY, RESOURCE_MIME_TYPE } from "./app";
-import { RESOURCE_URI_META_KEY } from "./app";
 export { PostMessageTransport } from "./message-transport";
 
 /**
@@ -100,12 +99,6 @@ export { PostMessageTransport } from "./message-transport";
  * const uri = getToolUiResourceUri({
  *   _meta: { ui: { resourceUri: "ui://server/app.html" } }
  * });
- *
- * // Deprecated flat format (still supported)
- * const uri = getToolUiResourceUri({
- *   _meta: { "ui/resourceUri": "ui://server/app.html" }
- * });
- * ```
  */
 export function getToolUiResourceUri(tool: {
   _meta?: Record<string, unknown>;
@@ -114,15 +107,12 @@ export function getToolUiResourceUri(tool: {
   const uiMeta = tool._meta?.ui as { resourceUri?: unknown } | undefined;
   let uri: unknown = uiMeta?.resourceUri;
 
-  // Fall back to deprecated flat format: _meta["ui/resourceUri"]
-  if (uri === undefined) {
-    uri = tool._meta?.[RESOURCE_URI_META_KEY];
-  }
-
   if (typeof uri === "string" && uri.startsWith("ui://")) {
     return uri;
   } else if (uri !== undefined) {
-    throw new Error(`Invalid UI resource URI: ${JSON.stringify(uri)}`);
+    throw new Error(
+      `Invalid UI resource URI: ${JSON.stringify(uri)}. URI must be a string and start with "ui://"`,
+    );
   }
   return undefined;
 }