diff --git a/src/tools/tasks.ts b/src/tools/tasks.ts
index b0d53e4..d3af824 100644
--- a/src/tools/tasks.ts
+++ b/src/tools/tasks.ts
@@ -90,7 +90,7 @@ export function createTaskTools(ctx: ToolContext): ToolDefinition<any>[] {
       parameters: UpdateTaskParams,
       async execute(_id: string, params: any) {
         const { task_id, ...fields } = params;
-        await ctx.trackerClient.updateTask(task_id, fields);
+        await ctx.trackerClient.updateTask(task_id, fields, ctx.agentSlug);
         return ok(`Task ${task_id} updated`);
       },
     },
diff --git a/src/tracker/client.ts b/src/tracker/client.ts
index d2fad3f..3781255 100644
--- a/src/tracker/client.ts
+++ b/src/tracker/client.ts
@@ -62,9 +62,10 @@ export class TrackerClient {
     return this.request('POST', `/api/v1/tasks?project_slug=${encodeURIComponent(projectSlug)}`, task);
   }
 
-  async updateTask(taskId: string, fields: Record<string, unknown>): Promise<void> {
-    this.log.info({ taskId, fields }, 'Updating task');
-    await this.request('PATCH', `/api/v1/tasks/${taskId}`, fields);
+  async updateTask(taskId: string, fields: Record<string, unknown>, actor?: string): Promise<void> {
+    this.log.info({ taskId, fields, actor }, 'Updating task');
+    const qs = actor ? `?actor=${encodeURIComponent(actor)}` : '';
+    await this.request('PATCH', `/api/v1/tasks/${taskId}${qs}`, fields);
   }
 
   async deleteTask(taskId: string): Promise<void> {