feat(core): support stable MCP SDK v2

Co-Authored-By: OpenAI Codex <codex@openai.com>

Author: sergical

dev-packages/e2e-tests/test-applications/cloudflare-mcp/package.json

@@ -14,10 +14,10 @@
     "test:dev": "TEST_ENV=development playwright test"
   },
   "dependencies": {
-    "@modelcontextprotocol/sdk": "^1.24.0",
+    "@modelcontextprotocol/server": "2.0.0",
     "@sentry/cloudflare": "file:../../packed/sentry-cloudflare-packed.tgz",
-    "agents": "0.3.10",
-    "zod": "^3.25.76"
+    "agents": "0.20.1",
+    "zod": "^4.2.0"
   },
   "devDependencies": {
     "@cloudflare/workers-types": "^4.20240725.0",
@@ -30,11 +30,5 @@
   "volta": {
     "node": "24.15.0",
     "extends": "../../package.json"
-  },
-  "pnpm": {
-    "overrides": {
-      "strip-literal": "~2.0.0",
-      "@modelcontextprotocol/sdk": "1.25.2"
-    }
   }
 }

dev-packages/e2e-tests/test-applications/cloudflare-mcp/src/index.ts

@@ -11,9 +11,55 @@
  * Learn more at https://developers.cloudflare.com/workers/
  */
 import * as Sentry from '@sentry/cloudflare';
-import { createMcpHandler } from 'agents/mcp';
-import * as z from 'zod';
-import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
+import { McpServer } from '@modelcontextprotocol/server';
+import { createMcpHandler } from 'agents/mcp/server';
+import { z } from 'zod';
+
+function createServer() {
+  const server = Sentry.wrapMcpServerWithSentry(
+    new McpServer({
+      name: 'cloudflare-mcp',
+      version: '2.0.0',
+    }),
+  );
+
+  server.registerTool(
+    'my-tool',
+    {
+      title: 'My Tool',
+      description: 'My Tool Description',
+      inputSchema: z.object({
+        message: z.string(),
+      }),
+    },
+    async ({ message }) => {
+      const span = Sentry.getActiveSpan();
+
+      await new Promise(resolve => setTimeout(resolve, 500));
+
+      if (span) {
+        span.setAttribute('mcp.tool.name', 'my-tool');
+        span.setAttribute('mcp.tool.extra', 'ƸӜƷ');
+        span.setAttribute('mcp.tool.input', JSON.stringify({ message }));
+      }
+
+      return {
+        content: [
+          {
+            type: 'text' as const,
+            text: `Tool my-tool: ${message}`,
+          },
+        ],
+      };
+    },
+  );
+
+  return server;
+}
+
+const mcpHandler = createMcpHandler(createServer, {
+  route: '/mcp',
+});
 
 export default Sentry.withSentry(
   (env: Env) => ({
@@ -31,54 +77,13 @@ export default Sentry.withSentry(
   }),
   {
     async fetch(request, env, ctx) {
-      const server = new McpServer({
-        name: 'cloudflare-mcp',
-        version: '1.0.0',
-      });
-
       const span = Sentry.getActiveSpan();
 
       if (span) {
         span.setAttribute('mcp.server.extra', ' /|\ ^._.^ /|\ ');
       }
 
-      server.registerTool(
-        'my-tool',
-        {
-          title: 'My Tool',
-          description: 'My Tool Description',
-          inputSchema: {
-            message: z.string(),
-          },
-        },
-        async ({ message }) => {
-          const span = Sentry.getActiveSpan();
-
-          // simulate a long running tool
-          await new Promise(resolve => setTimeout(resolve, 500));
-
-          if (span) {
-            span.setAttribute('mcp.tool.name', 'my-tool');
-            span.setAttribute('mcp.tool.extra', 'ƸӜƷ');
-            span.setAttribute('mcp.tool.input', JSON.stringify({ message }));
-          }
-
-          return {
-            content: [
-              {
-                type: 'text' as const,
-                text: `Tool my-tool: ${message}`,
-              },
-            ],
-          };
-        },
-      );
-
-      const handler = createMcpHandler(Sentry.wrapMcpServerWithSentry(server), {
-        route: '/mcp',
-      });
-
-      return handler(request, env, ctx);
+      return mcpHandler(request, env, ctx);
     },
   } satisfies ExportedHandler<Env>,
 );

dev-packages/e2e-tests/test-applications/cloudflare-mcp/tests/index.test.ts

@@ -1,111 +1,146 @@
 import { expect, test } from '@playwright/test';
 import { waitForRequest } from '@sentry-internal/test-utils';
 
-test('sends spans for MCP tool calls', async ({ baseURL }) => {
-  const spanRequestWaiter = waitForRequest('cloudflare-mcp', event => {
-    const transaction = event.envelope[1][0][1];
-    return typeof transaction !== 'string' && 'transaction' in transaction && transaction.transaction === 'POST /mcp';
-  });
+const APP_NAME = 'cloudflare-mcp';
+
+function getTransaction(eventData: Awaited<ReturnType<typeof waitForRequest>>) {
+  const event = eventData.envelope[1][0][1];
+  return typeof event !== 'string' && 'transaction' in event ? event : undefined;
+}
+
+function requireTransaction(eventData: Awaited<ReturnType<typeof waitForRequest>>) {
+  const event = getTransaction(eventData);
+  if (!event) {
+    throw new Error('Expected a transaction event');
+  }
+  return event;
+}
+
+test.describe.configure({ mode: 'serial' });
 
-  const spanMcpWaiter = waitForRequest('cloudflare-mcp', event => {
-    const transaction = event.envelope[1][0][1];
+test('sends spans for MCP 2026-07-28 tool calls', async ({ baseURL }) => {
+  const url = `${baseURL}/mcp?protocol=modern`;
+  const requestWaiter = waitForRequest(APP_NAME, eventData => {
+    const event = getTransaction(eventData);
+    return event?.transaction === 'POST /mcp' && event.contexts?.trace?.data?.['url.full'] === url;
+  });
+  const mcpWaiter = waitForRequest(APP_NAME, eventData => {
+    const event = getTransaction(eventData);
     return (
-      typeof transaction !== 'string' &&
-      'transaction' in transaction &&
-      transaction.transaction === 'tools/call my-tool'
+      event?.transaction === 'tools/call my-tool' &&
+      event.contexts?.trace?.data?.['mcp.protocol.version'] === '2026-07-28'
     );
   });
 
-  const response = await fetch(`${baseURL}/mcp`, {
+  const response = await fetch(url, {
     method: 'POST',
     headers: {
       'Content-Type': 'application/json',
       Accept: 'application/json, text/event-stream',
+      'MCP-Protocol-Version': '2026-07-28',
+      'Mcp-Method': 'tools/call',
+      'Mcp-Name': 'my-tool',
     },
     body: JSON.stringify({
       jsonrpc: '2.0',
-      id: 1,
+      id: 'modern-tool-call',
       method: 'tools/call',
       params: {
+        _meta: {
+          'io.modelcontextprotocol/protocolVersion': '2026-07-28',
+          'io.modelcontextprotocol/clientInfo': {
+            name: 'cloudflare-modern-client',
+            version: '2.0.0',
+          },
+          'io.modelcontextprotocol/clientCapabilities': {},
+        },
         name: 'my-tool',
         arguments: {
-          message: 'ʕっ•ᴥ•ʔっ',
+          message: 'modern protocol request',
         },
       },
     }),
   });
 
   expect(response.status).toBe(200);
+  await expect(response.json()).resolves.toMatchObject({
+    jsonrpc: '2.0',
+    id: 'modern-tool-call',
+    result: {
+      resultType: 'complete',
+      content: [{ type: 'text', text: 'Tool my-tool: modern protocol request' }],
+    },
+  });
 
-  const requestData = await spanRequestWaiter;
-  const mcpData = await spanMcpWaiter;
-
-  const requestEvent = requestData.envelope[1][0][1];
-  const mcpEvent = mcpData.envelope[1][0][1];
-
-  // Check that the events have contexts
-  // this is for TypeScript type safety
-  if (
-    typeof mcpEvent === 'string' ||
-    !('contexts' in mcpEvent) ||
-    typeof requestEvent === 'string' ||
-    !('contexts' in requestEvent)
-  ) {
-    throw new Error("Events don't have contexts");
-  }
+  const requestData = await requestWaiter;
+  const mcpData = await mcpWaiter;
+  const requestEvent = requireTransaction(requestData);
+  const mcpEvent = requireTransaction(mcpData);
+  const requestTrace = requestEvent.contexts?.trace;
+  const mcpTrace = mcpEvent.contexts?.trace;
 
-  expect(mcpEvent.contexts?.trace?.trace_id).toBe((mcpData.envelope[0].trace as any).trace_id);
-  expect(requestData.envelope[0].event_id).not.toBe(mcpData.envelope[0].event_id);
+  expect(requestTrace?.op).toBe('http.server');
+  expect(requestTrace?.data?.['mcp.server.extra']).toBe(' /|\ ^._.^ /|\ ');
+  expect(mcpTrace?.trace_id).toBe(requestTrace?.trace_id);
+  expect(mcpTrace?.parent_span_id).toBe(requestTrace?.span_id);
+  expect(mcpTrace?.op).toBe('mcp.server');
+  expect(mcpTrace?.origin).toBe('auto.function.mcp_server');
+  expect(mcpTrace?.status).toBe('ok');
+  expect(mcpTrace?.data?.['mcp.transport']).toBe('PerRequestHTTPServerTransport');
+  expect(mcpTrace?.data?.['network.transport']).toBe('tcp');
+  expect(mcpTrace?.data?.['mcp.protocol.version']).toBe('2026-07-28');
+  expect(mcpTrace?.data?.['mcp.client.name']).toBe('cloudflare-modern-client');
+  expect(mcpTrace?.data?.['mcp.client.version']).toBe('2.0.0');
+  expect(mcpTrace?.data?.['mcp.server.name']).toBe('cloudflare-mcp');
+  expect(mcpTrace?.data?.['mcp.server.version']).toBe('2.0.0');
+  expect(mcpTrace?.data?.['mcp.method.name']).toBe('tools/call');
+  expect(mcpTrace?.data?.['mcp.request.id']).toBe('modern-tool-call');
+  expect(mcpTrace?.data?.['mcp.tool.name']).toBe('my-tool');
+  expect(mcpTrace?.data?.['mcp.request.argument.message']).toBe('"modern protocol request"');
+  expect(mcpTrace?.data?.['mcp.tool.result.content_count']).toBe(1);
+  expect(mcpTrace?.data?.['mcp.tool.result.content']).toBe('Tool my-tool: modern protocol request');
+});
 
-  expect(requestEvent.contexts?.trace).toEqual({
-    span_id: expect.any(String),
-    trace_id: expect.any(String),
-    data: expect.objectContaining({
-      'sentry.origin': 'auto.http.cloudflare',
-      'sentry.op': 'http.server',
-      'sentry.source': 'url',
-      'sentry.sample_rate': 1,
-      'http.request.method': 'POST',
-      'url.path': '/mcp',
-      'url.full': 'http://localhost:38787/mcp',
-      'url.port': '38787',
-      'url.scheme': 'http:',
-      'server.address': 'localhost',
-      'http.request.body.size': 120,
-      'user_agent.original': 'node',
-      'http.request.header.content_type': 'application/json',
-      'network.protocol.name': 'HTTP/1.1',
-      'mcp.server.extra': ' /|\ ^._.^ /|\ ',
-      'http.response.status_code': 200,
-    }),
-    op: 'http.server',
-    status: 'ok',
-    origin: 'auto.http.cloudflare',
+test('keeps sending spans for legacy-compatible MCP tool calls', async ({ baseURL }) => {
+  const url = `${baseURL}/mcp?protocol=legacy`;
+  const mcpWaiter = waitForRequest(APP_NAME, eventData => {
+    const event = getTransaction(eventData);
+    return (
+      event?.transaction === 'tools/call my-tool' &&
+      event.contexts?.trace?.data?.['mcp.request.argument.message'] === '"legacy protocol request"'
+    );
   });
 
-  expect(mcpEvent.contexts?.trace).toEqual({
-    trace_id: expect.any(String),
-    parent_span_id: requestEvent.contexts?.trace?.span_id,
-    span_id: expect.any(String),
-    op: 'mcp.server',
-    origin: 'auto.function.mcp_server',
-    status: 'ok',
-    data: {
-      'sentry.origin': 'auto.function.mcp_server',
-      'sentry.op': 'mcp.server',
-      'sentry.source': 'route',
-      'mcp.transport': 'WorkerTransport',
-      'network.transport': 'unknown',
-      'network.protocol.version': '2.0',
-      'mcp.method.name': 'tools/call',
-      'mcp.request.id': '1',
-      'mcp.tool.name': 'my-tool',
-      'mcp.request.argument.message': '"ʕっ•ᴥ•ʔっ"',
-      'mcp.tool.extra': 'ƸӜƷ',
-      'mcp.tool.input': '{"message":"ʕっ•ᴥ•ʔっ"}',
-      'mcp.tool.result.content_count': 1,
-      'mcp.tool.result.content_type': 'text',
-      'mcp.tool.result.content': 'Tool my-tool: ʕっ•ᴥ•ʔっ',
+  const response = await fetch(url, {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      Accept: 'application/json, text/event-stream',
     },
+    body: JSON.stringify({
+      jsonrpc: '2.0',
+      id: 'legacy-tool-call',
+      method: 'tools/call',
+      params: {
+        name: 'my-tool',
+        arguments: {
+          message: 'legacy protocol request',
+        },
+      },
+    }),
   });
+
+  expect(response.status).toBe(200);
+
+  const mcpEvent = requireTransaction(await mcpWaiter);
+  const trace = mcpEvent.contexts?.trace;
+
+  expect(trace?.op).toBe('mcp.server');
+  expect(trace?.status).toBe('ok');
+  expect(trace?.data?.['mcp.transport']).toBe('WebStandardStreamableHTTPServerTransport');
+  expect(trace?.data?.['mcp.method.name']).toBe('tools/call');
+  expect(trace?.data?.['mcp.request.id']).toBe('legacy-tool-call');
+  expect(trace?.data?.['mcp.tool.name']).toBe('my-tool');
+  expect(trace?.data?.['mcp.protocol.version']).toBeUndefined();
+  expect(trace?.data?.['mcp.tool.result.content']).toBe('Tool my-tool: legacy protocol request');
 });

dev-packages/e2e-tests/test-applications/node-express-mcp-v2/package.json

@@ -12,17 +12,17 @@
   },
   "dependencies": {
     "@cfworker/json-schema": "^4.0.0",
-    "@modelcontextprotocol/server": "2.0.0-alpha.2",
-    "@modelcontextprotocol/node": "2.0.0-alpha.2",
+    "@modelcontextprotocol/node": "2.0.0",
+    "@modelcontextprotocol/server": "2.0.0",
     "@sentry/node": "file:../../packed/sentry-node-packed.tgz",
     "@types/express": "^4.17.21",
     "@types/node": "^18.19.1",
     "express": "^4.21.2",
     "typescript": "~5.0.0",
-    "zod": "^4.0.0"
+    "zod": "^4.2.0"
   },
   "devDependencies": {
-    "@modelcontextprotocol/client": "2.0.0-alpha.2",
+    "@modelcontextprotocol/client": "2.0.0",
     "@playwright/test": "~1.56.0",
     "@sentry-internal/test-utils": "link:../../../test-utils",
     "@sentry/core": "file:../../packed/sentry-core-packed.tgz"

dev-packages/e2e-tests/test-applications/node-express-mcp-v2/tests/mcp.test.ts

@@ -3,9 +3,7 @@ import { waitForTransaction } from '@sentry-internal/test-utils';
 import { Client } from '@modelcontextprotocol/client';
 import { StreamableHTTPClientTransport } from '@modelcontextprotocol/client';
 
-test('Should record transactions for MCP handlers using @modelcontextprotocol/sdk v2 (register* API)', async ({
-  baseURL,
-}) => {
+test('records transactions for stable MCP SDK v2 handlers using the register API', async ({ baseURL }) => {
   const transport = new StreamableHTTPClientTransport(new URL(`${baseURL}/mcp`));
 
   const client = new Client({