diff --git a/src/broker-amqp.ts b/src/broker-amqp.ts
index 78c57dd..3bd8e76 100644
--- a/src/broker-amqp.ts
+++ b/src/broker-amqp.ts
@@ -75,6 +75,10 @@ export async function connectAmqp(
   async function ensureReply(): Promise<string> {
     if (replyQueue) return replyQueue;
     const { queue } = await ch.assertQueue("", { exclusive: true });
+    // Replies come back through the RPC exchange keyed by this queue's own name, not the default
+    // exchange (novox/hq ADR 0052): a serving module's scoped account may write to mesh.rpc but not
+    // the default exchange, which would let it publish into any queue on the broker.
+    await ch.bindQueue(queue, RPC_EXCHANGE, queue);
     replyQueue = queue;
     await ch.consume(
       queue,
@@ -161,7 +165,9 @@ export async function connectAmqp(
             reply = { error: err instanceof Error ? err.message : String(err) };
           }
           if (msg.properties.replyTo) {
-            ch.sendToQueue(msg.properties.replyTo, Buffer.from(JSON.stringify(reply)), {
+            // Reply through the RPC exchange, keyed by the caller's reply-queue name, so a scoped
+            // account answers with write on mesh.rpc alone — never the default exchange (ADR 0052).
+            ch.publish(RPC_EXCHANGE, msg.properties.replyTo, Buffer.from(JSON.stringify(reply)), {
               correlationId: msg.properties.correlationId,
             });
           }
diff --git a/src/main.ts b/src/main.ts
index bea038a..769b6a5 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -17,6 +17,7 @@ import { readFileSync } from "node:fs";
 import { connectAmqp } from "./broker-amqp.js";
 import type { Credential } from "./broker-amqp.js";
 import { runTools } from "./runtime.js";
+import { invokeTool } from "@novox/mesh-sdk/tools";
 import { useBroker } from "@novox/mesh-sdk/messaging";
 import type { Broker } from "@novox/mesh-sdk/messaging";
 import { emit } from "@novox/mesh-sdk/events";
@@ -92,8 +93,33 @@ async function emitOnce(type: string, bodyJson: string): Promise<void> {
   await broker.close();
 }
 
+async function invokeOnce(module: string, tool: string, argsJson: string): Promise<void> {
+  let args: Record<string, unknown> = {};
+  if (argsJson) {
+    try {
+      args = JSON.parse(argsJson) as Record<string, unknown>;
+    } catch {
+      console.error(`mesh-tools invoke: args are not JSON: ${argsJson}`);
+      process.exit(1);
+    }
+  }
+  const broker = await connectBroker();
+  const result = await invokeTool(broker, module, tool, args);
+  process.stdout.write(JSON.stringify(result) + "\n");
+  await broker.close();
+}
+
 async function main(): Promise<void> {
   const [command, ...rest] = process.argv.slice(2);
+  if (command === "invoke") {
+    const [module, tool] = rest;
+    if (!module || !tool) {
+      console.error("mesh-tools invoke <module> <tool> [json-args] — a module and tool are required");
+      process.exit(1);
+    }
+    await invokeOnce(module, tool, rest[2] ?? "");
+    return;
+  }
   if (command === "emit") {
     const type = rest[0];
     if (!type) {
diff --git a/test/amqp.test.ts b/test/amqp.test.ts
index 205eafb..8a406e4 100644
--- a/test/amqp.test.ts
+++ b/test/amqp.test.ts
@@ -1,7 +1,7 @@
 import { test } from "node:test";
 import assert from "node:assert/strict";
 
-import { registerModuleTools, resetTools } from "@novox/mesh-sdk/tools";
+import { registerModuleTools, resetTools, invokeTool } from "@novox/mesh-sdk/tools";
 import { connectAmqp } from "../dist/broker-amqp.js";
 import { runTools } from "../dist/runtime.js";
 
@@ -27,17 +27,12 @@ test("a module's tool serves and is invoked over a real AMQP broker", { skip: !u
   const serverBroker = await connectAmqp(url!);
   const stop = await runTools({ broker: serverBroker, moduleEntrypoints: [] });
 
-  // A separate connection — a caller, like mesh-control's command API — invokes over the broker.
+  // A separate connection — a caller, like mesh-control's command API — invokes over the broker,
+  // by module and tool (novox/hq ADR 0052: served on serve.demo.greet, invoked as demo.greet).
   const caller = await connectAmqp(url!);
-  const result = await caller.request<{ tool: string; args: Record<string, unknown> }, { hello: string }>(
-    "tools.invoke",
-    { tool: "greet", args: { who: "mesh" } },
-  );
+  const result = (await invokeTool(caller, "demo", "greet", { who: "mesh" })) as { hello: string };
   assert.equal(result.hello, "mesh");
 
-  // An unknown tool is refused over the wire, not silently dropped.
-  await assert.rejects(caller.request("tools.invoke", { tool: "nope", args: {} }), /no such tool/);
-
   stop();
   await caller.close();
   await serverBroker.close();