chore(mcp): migrate agents to MCP SDK v2 packages

examples/mcp-elicitation/src/index.ts

@@ -1,57 +1,31 @@
-import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
-import {
-  createMcpHandler,
-  type TransportState,
-  WorkerTransport
-} from "agents/mcp";
+import { McpServer } from "@modelcontextprotocol/server";
+import { McpAgent } from "agents/mcp";
 import * as z from "zod";
-import { Agent, getAgentByName } from "agents";
-import { CfWorkerJsonSchemaValidator } from "@modelcontextprotocol/sdk/validation/cfworker-provider.js";
-import { env } from "cloudflare:workers";
-
-const STATE_KEY = "mcp_transport_state";
 
 interface State {
   counter: number;
 }
 
-export class MyAgent extends Agent<Cloudflare.Env, State> {
-  server = new McpServer(
-    {
-      name: "test",
-      version: "1.0.0"
-    },
-    {
-      jsonSchemaValidator: new CfWorkerJsonSchemaValidator()
-    }
-  );
-
-  transport = new WorkerTransport({
-    sessionIdGenerator: () => this.name,
-    storage: {
-      get: () => {
-        return this.ctx.storage.kv.get<TransportState>(STATE_KEY);
-      },
-      set: (state: TransportState) => {
-        this.ctx.storage.kv.put<TransportState>(STATE_KEY, state);
-      }
-    }
+export class MyAgent extends McpAgent<Cloudflare.Env, State> {
+  server = new McpServer({
+    name: "test",
+    version: "1.0.0"
   });
 
   initialState = {
     counter: 0
   };
 
-  onStart(): void | Promise<void> {
+  async init() {
     this.server.registerTool(
       "increase-counter",
       {
         description: "Increase the counter",
         inputSchema: {
           confirm: z.boolean().describe("Do you want to increase the counter?")
         }
       },
       async ({ confirm }, extra) => {
         if (!confirm) {
           return {
             content: [{ type: "text", text: "Counter increase cancelled." }]
@@ -73,7 +47,7 @@
                 required: ["amount"]
               }
             },
             { relatedRequestId: extra.requestId }
           );
 
           if (basicInfo.action !== "accept" || !basicInfo.content) {
@@ -113,19 +87,6 @@
       }
     );
   }
-
-  async onMcpRequest(request: Request) {
-    return createMcpHandler(this.server, {
-      transport: this.transport
-    })(request, this.env, {} as ExecutionContext);
-  }
 }
 
-export default {
-  async fetch(request: Request) {
-    const sessionId =
-      request.headers.get("mcp-session-id") ?? crypto.randomUUID();
-    const agent = await getAgentByName(env.MyAgent, sessionId);
-    return await agent.onMcpRequest(request);
-  }
-};
+export default MyAgent.serve("/mcp", { binding: "MyAgent" });

packages/agents/package.json

@@ -26,7 +26,8 @@
   "dependencies": {
     "@babel/plugin-proposal-decorators": "^7.29.0",
     "@cfworker/json-schema": "^4.1.1",
-    "@modelcontextprotocol/sdk": "1.29.0",
+    "@modelcontextprotocol/client": "^2.0.0-alpha.2",
+    "@modelcontextprotocol/server": "^2.0.0-alpha.2",
     "@rolldown/plugin-babel": "^0.2.3",
     "cron-schedule": "^6.0.0",
     "mimetext": "^3.0.28",

packages/agents/src/experimental/webmcp.ts

@@ -58,10 +58,8 @@
  * @experimental This API is not yet stable and may change.
  */
 
-import { Client } from "@modelcontextprotocol/sdk/client/index.js";
-import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
-import { ToolListChangedNotificationSchema } from "@modelcontextprotocol/sdk/types.js";
-
+import { Client } from "@modelcontextprotocol/client";
+import { StreamableHTTPClientTransport } from "@modelcontextprotocol/client";
 // ── WebMCP browser API surface (Chrome's navigator.modelContext) ─────
 
 interface ModelContextToolAnnotations {
@@ -193,7 +191,7 @@ class McpHttpClient {
     await this._client.connect(this._transport);
 
     this._client.setNotificationHandler(
-      ToolListChangedNotificationSchema,
+      "notifications/tools/list_changed",
       async () => {
         if (signal?.aborted) return;
         this._onToolsChanged?.();

packages/agents/src/index.ts

@@ -1,5 +1,5 @@
 import { AsyncLocalStorage } from "node:async_hooks";
-import type { Client } from "@modelcontextprotocol/sdk/client/index.js";
+import type { Client } from "@modelcontextprotocol/client";
 import {
   __DO_NOT_USE_WILL_BREAK__agentContext as agentContext,
   type AgentEmail
@@ -16,15 +16,15 @@ export {
   SUB_PREFIX
 } from "./sub-routing";
 export type { SubAgentPathMatch } from "./sub-routing";
-import type { SSEClientTransportOptions } from "@modelcontextprotocol/sdk/client/sse.js";
+import type { SSEClientTransportOptions } from "@modelcontextprotocol/client";
 import { signAgentHeaders } from "./email";
 
 import type {
   Prompt,
   Resource,
   ServerCapabilities,
   Tool
-} from "@modelcontextprotocol/sdk/types.js";
+} from "@modelcontextprotocol/server";
 import { parseCronExpression } from "cron-schedule";
 import { nanoid } from "nanoid";
 import { EmailMessage } from "cloudflare:email";

packages/agents/src/mcp/cf-validator.ts

@@ -0,0 +1,27 @@
+import type { Server } from "@modelcontextprotocol/server";
+import type { McpServer } from "@modelcontextprotocol/server";
+import { CfWorkerJsonSchemaValidator } from "@modelcontextprotocol/server/validators/cf-worker";
+
+/**
+ * Inject the Cloudflare Worker-compatible JSON Schema validator into an MCP
+ * server instance. The default Ajv validator uses `new Function()` which is
+ * blocked in Workers. This replaces it with `@cfworker/json-schema` which
+ * validates without code generation.
+ *
+ * Works with both `McpServer` (high-level) and `Server` (low-level).
+ */
+export function injectCfWorkerValidator(server: McpServer | Server): void {
+  // McpServer wraps Server as .server; raw Server is the object itself
+  const innerServer: Server =
+    "server" in server && typeof (server as McpServer).server === "object"
+      ? (server as McpServer).server
+      : (server as Server);
+
+  // _jsonSchemaValidator is private, but we need to override it to avoid
+  // the Ajv "Code generation from strings disallowed" error in Workers.
+  Object.defineProperty(innerServer, "_jsonSchemaValidator", {
+    value: new CfWorkerJsonSchemaValidator(),
+    writable: true,
+    configurable: true
+  });
+}

packages/agents/src/mcp/client-connection.ts

@@ -1,33 +1,25 @@
-import { Client } from "@modelcontextprotocol/sdk/client/index.js";
+import { Client } from "@modelcontextprotocol/client";
 import {
   SSEClientTransport,
   type SSEClientTransportOptions
-} from "@modelcontextprotocol/sdk/client/sse.js";
+} from "@modelcontextprotocol/client";
 import {
   StreamableHTTPClientTransport,
   type StreamableHTTPClientTransportOptions
-} from "@modelcontextprotocol/sdk/client/streamableHttp.js";
+} from "@modelcontextprotocol/client";
 // Import types directly from MCP SDK
-import type {
-  Prompt,
-  Resource,
-  Tool
-} from "@modelcontextprotocol/sdk/types.js";
+import type { Prompt, Resource, Tool } from "@modelcontextprotocol/client";
 import {
   type ClientCapabilities,
   type ElicitRequest,
-  ElicitRequestSchema,
   type ElicitResult,
   type ListPromptsResult,
   type ListResourceTemplatesResult,
   type ListResourcesResult,
   type ListToolsResult,
-  PromptListChangedNotificationSchema,
-  ResourceListChangedNotificationSchema,
   type ResourceTemplate,
-  type ServerCapabilities,
-  ToolListChangedNotificationSchema
-} from "@modelcontextprotocol/sdk/types.js";
+  type ServerCapabilities
+} from "@modelcontextprotocol/client";
 import { Emitter, type Event } from "../core/events";
 import type { MCPObservabilityEvent } from "../observability/mcp";
 import type { AgentMcpOAuthProvider } from "./do-oauth-client-provider";
@@ -168,7 +160,7 @@ export class MCPClientConnection {
     if (res.state === MCPConnectionState.CONNECTED && res.transport) {
       // Set up elicitation request handler after successful connection
       this.client.setRequestHandler(
-        ElicitRequestSchema,
+        "elicitation/create",
         async (request: ElicitRequest) => {
           return await this.handleElicitationRequest(request);
         }
@@ -492,7 +484,7 @@ export class MCPClientConnection {
       this._probingCapabilities
     ) {
       this.client.setNotificationHandler(
-        ToolListChangedNotificationSchema,
+        "notifications/tools/list_changed",
         async (_notification) => {
           this.tools = await this.fetchTools();
         }
@@ -512,7 +504,7 @@ export class MCPClientConnection {
       this._probingCapabilities
     ) {
       this.client.setNotificationHandler(
-        ResourceListChangedNotificationSchema,
+        "notifications/resources/list_changed",
         async (_notification) => {
           this.resources = await this.fetchResources();
         }
@@ -532,7 +524,7 @@ export class MCPClientConnection {
       this._probingCapabilities
     ) {
       this.client.setNotificationHandler(
-        PromptListChangedNotificationSchema,
+        "notifications/prompts/list_changed",
         async (_notification) => {
           this.prompts = await this.fetchPrompts();
         }
@@ -619,7 +611,7 @@ export class MCPClientConnection {
     _request: ElicitRequest
   ): Promise<ElicitResult> {
     // Elicitation handling must be implemented by the platform
-    // For MCP servers, this should be handled by McpAgent.elicitInput()
+    // For MCP servers, this should be handled by server.server.elicitInput()
     throw new Error(
       "Elicitation handler must be implemented for your platform. Override handleElicitationRequest method."
     );

packages/agents/src/mcp/client-transports.ts

@@ -2,23 +2,23 @@
  * Deprecated transport wrappers
  */
 
-import { SSEClientTransport } from "@modelcontextprotocol/sdk/client/sse.js";
-import type { SSEClientTransportOptions } from "@modelcontextprotocol/sdk/client/sse.js";
-import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
-import type { StreamableHTTPClientTransportOptions } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
+import { SSEClientTransport } from "@modelcontextprotocol/client";
+import type { SSEClientTransportOptions } from "@modelcontextprotocol/client";
+import { StreamableHTTPClientTransport } from "@modelcontextprotocol/client";
+import type { StreamableHTTPClientTransportOptions } from "@modelcontextprotocol/client";
 
 let didWarnAboutSSEEdgeClientTransport = false;
 
 /**
- * @deprecated Use SSEClientTransport from @modelcontextprotocol/sdk/client/sse.js instead. This alias will be removed in the next major version.
+ * @deprecated Use SSEClientTransport from @modelcontextprotocol/client instead. This alias will be removed in the next major version.
  */
 export class SSEEdgeClientTransport extends SSEClientTransport {
   constructor(url: URL, options: SSEClientTransportOptions) {
     super(url, options);
     if (!didWarnAboutSSEEdgeClientTransport) {
       didWarnAboutSSEEdgeClientTransport = true;
       console.warn(
-        "SSEEdgeClientTransport is deprecated. Use SSEClientTransport from @modelcontextprotocol/sdk/client/sse.js instead. SSEEdgeClientTransport will be removed in the next major version."
+        "SSEEdgeClientTransport is deprecated. Use SSEClientTransport from @modelcontextprotocol/client instead. SSEEdgeClientTransport will be removed in the next major version."
       );
     }
   }
@@ -27,15 +27,15 @@ export class SSEEdgeClientTransport extends SSEClientTransport {
 let didWarnAboutStreamableHTTPEdgeClientTransport = false;
 
 /**
- * @deprecated Use StreamableHTTPClientTransport from @modelcontextprotocol/sdk/client/streamableHttp.js instead. This alias will be removed in the next major version.
+ * @deprecated Use StreamableHTTPClientTransport from @modelcontextprotocol/client instead. This alias will be removed in the next major version.
  */
 export class StreamableHTTPEdgeClientTransport extends StreamableHTTPClientTransport {
   constructor(url: URL, options: StreamableHTTPClientTransportOptions) {
     super(url, options);
     if (!didWarnAboutStreamableHTTPEdgeClientTransport) {
       didWarnAboutStreamableHTTPEdgeClientTransport = true;
       console.warn(
-        "StreamableHTTPEdgeClientTransport is deprecated. Use StreamableHTTPClientTransport from @modelcontextprotocol/sdk/client/streamableHttp.js instead. StreamableHTTPEdgeClientTransport will be removed in the next major version."
+        "StreamableHTTPEdgeClientTransport is deprecated. Use StreamableHTTPClientTransport from @modelcontextprotocol/client instead. StreamableHTTPEdgeClientTransport will be removed in the next major version."
       );
     }
   }