diff --git a/index.d.ts b/index.d.ts
index b5453b0..b743902 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -198,8 +198,30 @@ namespace WebMCP {
         annotations?: ToolAnnotations;
     }
 
+    /**
+     * Initialization options for a `ToolActivatedEvent`.
+     */
+    type ToolActivatedEventInit = globalThis.ToolActivatedEventInit;
+
+    /**
+     * Event dispatched at a `ModelContext` when the execution of a tool begins.
+     */
+    type ToolActivatedEvent = globalThis.ToolActivatedEvent;
+
+    /**
+     * Initialization options for a `ToolCancelEvent`.
+     */
+    type ToolCancelEventInit = globalThis.ToolCancelEventInit;
+
+    /**
+     * Event dispatched at a `ModelContext` when the execution of a tool is cancelled.
+     */
+    type ToolCancelEvent = globalThis.ToolCancelEvent;
+
     interface ModelContextEventMap {
         "toolchange": Event;
+        "toolactivated": ToolActivatedEvent;
+        "toolcancel": ToolCancelEvent;
     }
 
     /**
@@ -234,6 +256,14 @@ namespace WebMCP {
          * Event handler for the toolchange event.
          */
         ontoolchange: ((this: ModelContext, ev: Event) => any) | null;
+        /**
+         * Event handler for the toolactivated event.
+         */
+        ontoolactivated: ((this: ModelContext, ev: ToolActivatedEvent) => any) | null;
+        /**
+         * Event handler for the toolcancel event.
+         */
+        ontoolcancel: ((this: ModelContext, ev: ToolCancelEvent) => any) | null;
 
         addEventListener<K extends keyof ModelContextEventMap>(type: K, listener: (this: ModelContext, ev: ModelContextEventMap[K]) => any, options?: boolean | AddEventListenerOptions): void;
         addEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;
@@ -249,6 +279,50 @@ interface Document {
      */
     readonly modelContext?: WebMCP.ModelContext;
 }
+
+interface ToolActivatedEventInit extends EventInit {
+    /**
+     * The name of the tool whose execution has started.
+     */
+    toolName?: string;
+}
+
+/**
+ * The event dispatched at a `ModelContext` object when the execution of a tool begins.
+ */
+interface ToolActivatedEvent extends Event {
+    /**
+     * The name of the tool whose execution has started.
+     */
+    readonly toolName: string;
+}
+
+var ToolActivatedEvent: {
+    prototype: ToolActivatedEvent;
+    new(type: string, eventInitDict?: ToolActivatedEventInit): ToolActivatedEvent;
+};
+
+interface ToolCancelEventInit extends EventInit {
+    /**
+     * The name of the tool whose execution was cancelled.
+     */
+    toolName?: string;
+}
+
+/**
+ * The event dispatched at a `ModelContext` object when the execution of a tool is cancelled.
+ */
+interface ToolCancelEvent extends Event {
+    /**
+     * The name of the tool whose execution was cancelled.
+     */
+    readonly toolName: string;
+}
+
+var ToolCancelEvent: {
+    prototype: ToolCancelEvent;
+    new(type: string, eventInitDict?: ToolCancelEventInit): ToolCancelEvent;
+};
 }
 
 export type { WebMCP };
diff --git a/index.test-d.ts b/index.test-d.ts
index 3c11c54..56d0505 100644
--- a/index.test-d.ts
+++ b/index.test-d.ts
@@ -189,3 +189,47 @@ test('supports executeTool', async () => {
     }>();
 });
 
+test('supports the toolchange, toolactivated, and toolcancel events', () => {
+    document.modelContext?.addEventListener('toolchange', (event) => {
+        expectTypeOf(event).toEqualTypeOf<Event>();
+    });
+
+    document.modelContext?.addEventListener('toolactivated', (event) => {
+        expectTypeOf(event).toEqualTypeOf<ToolActivatedEvent>();
+        expectTypeOf(event.toolName).toEqualTypeOf<string>();
+    });
+
+    document.modelContext?.addEventListener('toolcancel', (event) => {
+        expectTypeOf(event).toEqualTypeOf<ToolCancelEvent>();
+        expectTypeOf(event.toolName).toEqualTypeOf<string>();
+    });
+
+    if (document.modelContext) {
+        document.modelContext.ontoolchange = (event) => {
+            expectTypeOf(event).toEqualTypeOf<Event>();
+        };
+        document.modelContext.ontoolactivated = (event) => {
+            expectTypeOf(event).toEqualTypeOf<ToolActivatedEvent>();
+        };
+        document.modelContext.ontoolcancel = (event) => {
+            expectTypeOf(event).toEqualTypeOf<ToolCancelEvent>();
+        };
+        document.modelContext.ontoolchange = null;
+        document.modelContext.ontoolactivated = null;
+        document.modelContext.ontoolcancel = null;
+    }
+
+    expectTypeOf(new ToolActivatedEvent('toolactivated')).toEqualTypeOf<ToolActivatedEvent>();
+    expectTypeOf(new ToolActivatedEvent('toolactivated', { toolName: 'search', bubbles: true }))
+        .toEqualTypeOf<ToolActivatedEvent>();
+    expectTypeOf(new ToolCancelEvent('toolcancel', { toolName: 'search' })).toEqualTypeOf<ToolCancelEvent>();
+
+    expectTypeOf<ToolActivatedEvent>().toExtend<Event>();
+    expectTypeOf<ToolCancelEvent>().toExtend<Event>();
+    expectTypeOf<WebMCP.ToolActivatedEvent>().toEqualTypeOf<ToolActivatedEvent>();
+    expectTypeOf<WebMCP.ToolCancelEvent>().toEqualTypeOf<ToolCancelEvent>();
+    expectTypeOf<WebMCP.ToolActivatedEventInit>().toEqualTypeOf<ToolActivatedEventInit>();
+    expectTypeOf<WebMCP.ToolCancelEventInit>().toEqualTypeOf<ToolCancelEventInit>();
+    expectTypeOf<ToolActivatedEventInit['toolName']>().toEqualTypeOf<string | undefined>();
+    expectTypeOf<ToolCancelEventInit['toolName']>().toEqualTypeOf<string | undefined>();
+});