@@ -52,9 +52,6 @@ export function continueMcpTrace<T>(params: unknown, callback: (links: SpanLink[
 /**
  * Returns a copy of an outgoing request or notification with the active trace context added to `params._meta`, so the
  * receiving side can continue the trace. Messages that already carry trace context are returned unchanged.
- *
- * `traceparent` is always added, independent of the `propagateTraceparent` option: that option guards HTTP requests
- * against CORS failures, which do not apply here, and W3C Trace Context is what non-Sentry MCP peers read.
  */
 export function injectMcpTraceContext<M extends JsonRpcRequest | JsonRpcNotification>(message: M): M {
   const meta = message.params?._meta;
@@ -65,7 +62,13 @@ export function injectMcpTraceContext<M extends JsonRpcRequest | JsonRpcNotifica
     return message;
   }
 
-  const { 'sentry-trace': sentryTrace, baggage, traceparent } = getTraceData({ propagateTraceparent: true });
+  const {
+    'sentry-trace': sentryTrace,
+    baggage,
+    traceparent,
+  } = getTraceData({
+    propagateTraceparent: getClient()?.getOptions().propagateTraceparent,
+  });
   if (!sentryTrace) {
     return message;
   }
 
@@ -147,11 +147,7 @@ describe('MCP server trace propagation via params._meta', () => {
 
 describe('MCP server trace injection into outgoing params._meta', () => {
   beforeEach(() => {
-    const client = new TestClient(
-      getDefaultTestClientOptions({ dsn: 'https://public@dsn.ingest.sentry.io/1337', tracesSampleRate: 1 }),
-    );
-    setCurrentClient(client);
-    client.init();
+    initClient({ dsn: 'https://public@dsn.ingest.sentry.io/1337', propagateTraceparent: true });
   });
 
   afterEach(() => {
@@ -222,6 +218,20 @@ describe('MCP server trace injection into outgoing params._meta', () => {
     });
   });
 
+  it('only injects traceparent when propagateTraceparent is enabled', async () => {
+    initClient({ dsn: 'https://public@dsn.ingest.sentry.io/1337' });
+    const { send, originalSend } = wrappedSend();
+
+    await startSpan({ name: 'tools/call get-weather' }, () => send({ jsonrpc: '2.0', method: 'ping', id: 1 }));
+
+    expect(originalSend).toHaveBeenCalledWith({
+      jsonrpc: '2.0',
+      method: 'ping',
+      id: 1,
+      params: { _meta: { 'sentry-trace': expect.any(String), baggage: expect.any(String) } },
+    });
+  });
+
   it('keeps existing _meta entries and adds params when there are none', async () => {
     const { send, originalSend } = wrappedSend();