diff --git a/docs/patterns.md b/docs/patterns.md
index dc29b8c..ab4a9f1 100644
--- a/docs/patterns.md
+++ b/docs/patterns.md
@@ -20,12 +20,13 @@ Set {@link types!McpUiToolMeta.visibility Tool.\_meta.ui.visibility} to `["app"]
 
 {@includeCode ./patterns.tsx#authenticatedCalls}
 
-## [TODO] Giving errors back to model
+## Giving errors back to model
 
-- Before app runs: validate inputs in tool call
-- After it runs: use `updateModelContext`
+**Server-side**: Tool handler validates inputs and returns `{ isError: true, content: [...] }`. The model receives this error through the normal tool call response.
 
-{@includeCode ./patterns.tsx#errorsToModel}
+**Client-side**: If a runtime error occurs (e.g., API failure, permission denied, resource unavailable), use {@link app!App.updateModelContext updateModelContext} to inform the model:
+
+{@includeCode ../src/app.examples.ts#App_updateModelContext_reportError}
 
 ## Matching host styling (CSS variables, theme, and fonts)
 
diff --git a/docs/patterns.tsx b/docs/patterns.tsx
index c481ad3..a6fd259 100644
--- a/docs/patterns.tsx
+++ b/docs/patterns.tsx
@@ -27,17 +27,6 @@ function authenticatedCalls(app: App) {
   //#endregion authenticatedCalls
 }
 
-/**
- * Example: Giving errors back to model
- */
-function errorsToModel(app: App) {
-  //#region errorsToModel
-  // Before app runs: validate inputs in tool call
-  // After it runs: updateModelContext
-  // TODO: Complete implementation
-  //#endregion errorsToModel
-}
-
 /**
  * Example: Unified host styling (theme, CSS variables, fonts)
  */
@@ -132,7 +121,6 @@ function migrateFromOpenai() {
 
 // Suppress unused variable warnings
 void authenticatedCalls;
-void errorsToModel;
 void hostStylingVanillaJs;
 void hostStylingReact;
 void persistData;
diff --git a/src/app.examples.ts b/src/app.examples.ts
index bf6f9dc..c360837 100644
--- a/src/app.examples.ts
+++ b/src/app.examples.ts
@@ -364,6 +364,28 @@ async function App_updateModelContext_structuredContent(app: App) {
   //#endregion App_updateModelContext_structuredContent
 }
 
+/**
+ * Example: Report runtime error to model.
+ */
+async function App_updateModelContext_reportError(app: App) {
+  //#region App_updateModelContext_reportError
+  try {
+    const _stream = await navigator.mediaDevices.getUserMedia({ audio: true });
+    // ... use _stream for transcription
+  } catch (err) {
+    // Inform the model that the app is in a degraded state
+    await app.updateModelContext({
+      content: [
+        {
+          type: "text",
+          text: "Error: transcription unavailable",
+        },
+      ],
+    });
+  }
+  //#endregion App_updateModelContext_reportError
+}
+
 /**
  * Example: Open documentation link.
  */
diff --git a/src/app.ts b/src/app.ts
index 0628029..3408526 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -674,6 +674,9 @@ export class App extends Protocol<AppRequest, AppNotification, AppResult> {
    * @example Update with structured content
    * {@includeCode ./app.examples.ts#App_updateModelContext_structuredContent}
    *
+   * @example Report runtime error to model
+   * {@includeCode ./app.examples.ts#App_updateModelContext_reportError}
+   *
    * @returns Promise that resolves when the context update is acknowledged
    */
   updateModelContext(