diff --git a/imessage-mcp/src/index.ts b/imessage-mcp/src/index.ts
index f50980a..f544bcb 100644
--- a/imessage-mcp/src/index.ts
+++ b/imessage-mcp/src/index.ts
@@ -26,6 +26,7 @@ import { getNewMessages } from './tools/get-new-messages';
 import { listDisplayRules } from './tools/list-rules';
 import { addDisplayRule } from './tools/add-rule';
 import { removeDisplayRule } from './tools/remove-rule';
+import { restartService, RESTARTABLE_SERVICES, type ServiceName } from './tools/restart-service';
 import { shutdown } from './db';
 
 const TOOLS = [
@@ -277,6 +278,21 @@ const TOOLS = [
       },
     },
   },
+  {
+    name: 'restart_service',
+    description: 'Restart a mac-sync messaging service to clear a stalled send pipeline, without a reboot. Services: mac-sync (the macOS sync agent), mac-sync-server, imagent (iMessage delivery daemon), messages (Messages.app), or all (bounces the whole pipeline in order).',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        service: {
+          type: 'string',
+          enum: [...RESTARTABLE_SERVICES],
+          description: 'Which service to restart, or "all" to bounce the whole pipeline in order',
+        },
+      },
+      required: ['service'],
+    },
+  },
 ];
 
 async function main(): Promise<void> {
@@ -415,6 +431,11 @@ async function dispatch(name: string, args: unknown): Promise<string> {
       const params = args as { rule_id?: string };
       return removeDisplayRule({ rule_id: params.rule_id ?? '' });
     }
+    case 'restart_service': {
+      const params = args as { service?: string };
+      if (!params.service) throw new Error('service is required');
+      return restartService({ service: params.service as ServiceName });
+    }
     default:
       throw new Error(`Unknown tool: ${name}`);
   }
diff --git a/imessage-mcp/src/tools/restart-service.ts b/imessage-mcp/src/tools/restart-service.ts
new file mode 100644
index 0000000..ff4949b
--- /dev/null
+++ b/imessage-mcp/src/tools/restart-service.ts
@@ -0,0 +1,140 @@
+import { exec } from 'node:child_process';
+import { promisify } from 'node:util';
+
+const execAsync = promisify(exec);
+
+/**
+ * Services involved in the iMessage send pipeline that this tool can bounce.
+ *
+ *   send_queue (Postgres) → mac-sync-server → mac-sync (MacSyncApp agent)
+ *                         → Messages.app → imagent → delivery
+ *
+ * When sends stall, restarting the relevant layer (or `all`) clears most
+ * stuck states without a full reboot.
+ */
+export const RESTARTABLE_SERVICES = [
+  'mac-sync',
+  'mac-sync-server',
+  'imagent',
+  'messages',
+  'all',
+] as const;
+
+export type ServiceName = (typeof RESTARTABLE_SERVICES)[number];
+
+interface RestartServiceParams {
+  service: ServiceName;
+}
+
+const LAUNCHD_LABEL: Record<'mac-sync' | 'mac-sync-server', string> = {
+  'mac-sync': 'com.lilith.mac-sync',
+  'mac-sync-server': 'com.lilith.mac-sync-server',
+};
+
+const EXEC_OPTS = { timeout: 15_000 } as const;
+
+function errMsg(err: unknown): string {
+  return err instanceof Error ? err.message : String(err);
+}
+
+function delay(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+/** Restart a launchd-managed agent via `kickstart -k` and report its new PID. */
+async function restartLaunchdJob(key: 'mac-sync' | 'mac-sync-server'): Promise<string> {
+  const label = LAUNCHD_LABEL[key];
+  const uid = process.getuid?.() ?? 0;
+  try {
+    await execAsync(`launchctl kickstart -k gui/${uid}/${label}`, EXEC_OPTS);
+  } catch (err) {
+    return `${key}: kickstart failed — ${errMsg(err)}`;
+  }
+  await delay(2_000);
+  try {
+    const { stdout } = await execAsync(`launchctl list | grep ${label} || true`, EXEC_OPTS);
+    const pid = stdout.trim().split(/\s+/)[0];
+    return pid && pid !== '-'
+      ? `${key}: restarted (pid ${pid})`
+      : `${key}: kickstart issued, not yet listed`;
+  } catch (err) {
+    return `${key}: kickstart issued, verify failed — ${errMsg(err)}`;
+  }
+}
+
+/** Kill imagent (the iMessage delivery daemon); launchd respawns it. */
+async function restartImagent(): Promise<string> {
+  try {
+    await execAsync('killall imagent', EXEC_OPTS);
+  } catch {
+    // killall exits non-zero when no process matched — imagent respawns anyway.
+  }
+  await delay(2_500);
+  try {
+    const { stdout } = await execAsync('pgrep -x imagent || true', EXEC_OPTS);
+    const pid = stdout.trim().split('\n')[0];
+    return pid ? `imagent: restarted (pid ${pid})` : 'imagent: killed, awaiting respawn';
+  } catch (err) {
+    return `imagent: killed, verify failed — ${errMsg(err)}`;
+  }
+}
+
+/** Force-quit Messages.app and relaunch it. */
+async function restartMessages(): Promise<string> {
+  try {
+    await execAsync('killall Messages', EXEC_OPTS);
+  } catch {
+    // Not running — fine, the open below starts it fresh.
+  }
+  await delay(2_000);
+  try {
+    await execAsync('open -a Messages', EXEC_OPTS);
+    return 'messages: relaunched';
+  } catch (err) {
+    return `messages: relaunch failed — ${errMsg(err)}`;
+  }
+}
+
+async function restartOne(service: Exclude<ServiceName, 'all'>): Promise<string> {
+  switch (service) {
+    case 'mac-sync':
+    case 'mac-sync-server':
+      return restartLaunchdJob(service);
+    case 'imagent':
+      return restartImagent();
+    case 'messages':
+      return restartMessages();
+  }
+}
+
+/**
+ * Restart one mac-sync messaging service, or `all` of them in pipeline order
+ * (imagent → messages → mac-sync-server → mac-sync). Use when sends stall.
+ */
+export async function restartService(params: RestartServiceParams): Promise<string> {
+  const { service } = params;
+
+  if (!RESTARTABLE_SERVICES.includes(service)) {
+    throw new Error(
+      `restart_service: unknown service "${service}". ` +
+        `Valid: ${RESTARTABLE_SERVICES.join(', ')}`,
+    );
+  }
+
+  if (service === 'all') {
+    const order: Exclude<ServiceName, 'all'>[] = [
+      'imagent',
+      'messages',
+      'mac-sync-server',
+      'mac-sync',
+    ];
+    const results: string[] = [];
+    for (const svc of order) {
+      results.push(await restartOne(svc));
+    }
+    return ['Restarted all services:', ...results.map((r) => `  ${r}`)].join('\n');
+  }
+
+  const result = await restartOne(service);
+  return result;
+}