Raw request propagation in tools - passed to callbacks via RequestHandlerExtra<ServerRequest, ServerNotification>

src/client/index.test.ts

@@ -21,7 +21,14 @@ import {
 import { Transport } from "../shared/transport.js";
 import { Server } from "../server/index.js";
 import { InMemoryTransport } from "../inMemory.js";
-
+import { RequestInfo } from "../server/types/types.js";
+
+const mockRequestInfo: RequestInfo = {
+  headers: {
+    'content-type': 'application/json',
+    'accept': 'application/json',
+  },
+};
 /***
  * Test: Initialize with Matching Protocol Version
  */
@@ -43,7 +50,7 @@ test("should initialize with matching protocol version", async () => {
             },
             instructions: "test instructions",
           },
-        });
+        }, { requestInfo: mockRequestInfo });
       }
       return Promise.resolve();
     }),
@@ -101,7 +108,7 @@ test("should initialize with supported older protocol version", async () => {
               version: "1.0",
             },
           },
-        });
+        }, { requestInfo: mockRequestInfo });
       }
       return Promise.resolve();
     }),
@@ -151,7 +158,7 @@ test("should reject unsupported protocol version", async () => {
               version: "1.0",
             },
           },
-        });
+        }, { requestInfo: mockRequestInfo });
       }
       return Promise.resolve();
     }),

src/server/index.test.ts

@@ -20,6 +20,14 @@ import {
 import { Transport } from "../shared/transport.js";
 import { InMemoryTransport } from "../inMemory.js";
 import { Client } from "../client/index.js";
+import { RequestInfo } from "./types/types.js";
+
+const mockRequestInfo: RequestInfo = {
+  headers: {
+    'content-type': 'application/json',
+    'traceparent': '00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01',
+  },
+};
 
 test("should accept latest protocol version", async () => {
   let sendPromiseResolve: (value: unknown) => void;
@@ -78,7 +86,7 @@ test("should accept latest protocol version", async () => {
         version: "1.0",
       },
     },
-  });
+  }, { requestInfo: mockRequestInfo });
 
   await expect(sendPromise).resolves.toBeUndefined();
 });
@@ -139,7 +147,7 @@ test("should accept supported older protocol version", async () => {
         version: "1.0",
       },
     },
-  });
+  }, { requestInfo: mockRequestInfo });
 
   await expect(sendPromise).resolves.toBeUndefined();
 });
@@ -199,7 +207,7 @@ test("should handle unsupported protocol version", async () => {
         version: "1.0",
       },
     },
-  });
+  }, { requestInfo: mockRequestInfo });
 
   await expect(sendPromise).resolves.toBeUndefined();
 });

src/server/mcp.test.ts

@@ -19,8 +19,16 @@ import {
 import { ResourceTemplate } from "./mcp.js";
 import { completable } from "./completable.js";
 import { UriTemplate } from "../shared/uriTemplate.js";
+import { RequestInfo } from "./types/types.js";
 import { getDisplayName } from "../shared/metadataUtils.js";
 
+const mockRequestInfo: RequestInfo = {
+  headers: {
+    'content-type': 'application/json',
+    'accept': 'application/json',
+  },
+};
+
 describe("McpServer", () => {
   /***
    * Test: Basic Server Instance
@@ -214,7 +222,8 @@ describe("ResourceTemplate", () => {
       signal: abortController.signal,
       requestId: 'not-implemented',
       sendRequest: () => { throw new Error("Not implemented") },
-      sendNotification: () => { throw new Error("Not implemented") }
+      sendNotification: () => { throw new Error("Not implemented") }, 
+      requestInfo: mockRequestInfo
     });
     expect(result?.resources).toHaveLength(1);
     expect(list).toHaveBeenCalled();

src/server/sse.test.ts

@@ -1,20 +1,146 @@
 import http from 'http'; 
 import { jest } from '@jest/globals';
 import { SSEServerTransport } from './sse.js'; 
+import { McpServer } from './mcp.js';
+import { createServer, type Server } from "node:http";
+import { AddressInfo } from "node:net";
+import { z } from 'zod';
+import { CallToolResult, JSONRPCMessage } from 'src/types.js';
 
 const createMockResponse = () => {
   const res = {
-    writeHead: jest.fn<http.ServerResponse['writeHead']>(),
-    write: jest.fn<http.ServerResponse['write']>().mockReturnValue(true),
-    on: jest.fn<http.ServerResponse['on']>(),
+    writeHead: jest.fn<http.ServerResponse['writeHead']>().mockReturnThis(),
+    write: jest.fn<http.ServerResponse['write']>().mockReturnThis(),
+    on: jest.fn<http.ServerResponse['on']>().mockReturnThis(),
+    end: jest.fn<http.ServerResponse['end']>().mockReturnThis(),
   };
-  res.writeHead.mockReturnThis();
-  res.on.mockReturnThis();
 
-  return res as unknown as http.ServerResponse;
+  return res as unknown as jest.Mocked<http.ServerResponse>;
 };
 
+/**
+ * Helper to create and start test HTTP server with MCP setup
+ */
+async function createTestServerWithSse(args: {
+  mockRes: http.ServerResponse;
+}): Promise<{
+  server: Server;
+  transport: SSEServerTransport;
+  mcpServer: McpServer;
+  baseUrl: URL;
+  sessionId: string
+  serverPort: number;
+}> {
+  const mcpServer = new McpServer(
+    { name: "test-server", version: "1.0.0" },
+    { capabilities: { logging: {} } }
+  );
+
+  mcpServer.tool(
+    "greet",
+    "A simple greeting tool",
+    { name: z.string().describe("Name to greet") },
+    async ({ name }): Promise<CallToolResult> => {
+      return { content: [{ type: "text", text: `Hello, ${name}!` }] };
+    }
+  );
+
+  const endpoint = '/messages';
+
+  const transport = new SSEServerTransport(endpoint, args.mockRes);
+  const sessionId = transport.sessionId;
+
+  await mcpServer.connect(transport);
+
+  const server = createServer(async (req, res) => {
+    try {
+        await transport.handlePostMessage(req, res);
+    } catch (error) {
+      console.error("Error handling request:", error);
+      if (!res.headersSent) res.writeHead(500).end();
+    }
+  });
+
+  const baseUrl = await new Promise<URL>((resolve) => {
+    server.listen(0, "127.0.0.1", () => {
+      const addr = server.address() as AddressInfo;
+      resolve(new URL(`http://127.0.0.1:${addr.port}`));
+    });
+  });
+
+  const port = (server.address() as AddressInfo).port;
+
+  return { server, transport, mcpServer, baseUrl, sessionId, serverPort: port };
+}
+
+async function readAllSSEEvents(response: Response): Promise<string[]> {
+  const reader = response.body?.getReader();
+  if (!reader) throw new Error('No readable stream');
+
+  const events: string[] = [];
+  const decoder = new TextDecoder();
+
+  try {
+    while (true) {
+      const { done, value } = await reader.read();
+      if (done) break;
+
+      if (value) {
+        events.push(decoder.decode(value));
+      }
+    }
+  } finally {
+    reader.releaseLock();
+  }
+
+  return events;
+}
+
+/**
+ * Helper to send JSON-RPC request
+ */
+async function sendSsePostRequest(baseUrl: URL, message: JSONRPCMessage | JSONRPCMessage[], sessionId?: string, extraHeaders?: Record<string, string>): Promise<Response> {
+  const headers: Record<string, string> = {
+    "Content-Type": "application/json",
+    Accept: "application/json, text/event-stream",
+    ...extraHeaders
+  };
+
+  if (sessionId) {
+    baseUrl.searchParams.set('sessionId', sessionId);
+  }
+
+  return fetch(baseUrl, {
+    method: "POST",
+    headers,
+    body: JSON.stringify(message),
+  });
+}
+
 describe('SSEServerTransport', () => {
+
+  async function initializeServer(baseUrl: URL): Promise<void> {
+    const response = await sendSsePostRequest(baseUrl, {
+      jsonrpc: "2.0",
+      method: "initialize",
+      params: {
+        clientInfo: { name: "test-client", version: "1.0" },
+        protocolVersion: "2025-03-26",
+        capabilities: {
+        },
+      },
+
+      id: "init-1",
+    } as JSONRPCMessage);
+
+    expect(response.status).toBe(202);
+
+    const text = await readAllSSEEvents(response);
+
+    expect(text).toHaveLength(1);
+    expect(text[0]).toBe('Accepted');
+  }
+
   describe('start method', () => { 
     it('should correctly append sessionId to a simple relative endpoint', async () => { 
       const mockRes = createMockResponse();
@@ -105,5 +231,71 @@ describe('SSEServerTransport', () => {
         `event: endpoint\ndata: /?sessionId=${expectedSessionId}\n\n`
       );
     });
+
+     /***
+   * Test: Tool With Request Info
+   */
+  it("should pass request info to tool callback", async () => {
+    const mockRes = createMockResponse();
+    const { mcpServer, baseUrl, sessionId, serverPort } = await createTestServerWithSse({ mockRes });
+    await initializeServer(baseUrl);
+
+    mcpServer.tool(
+      "test-request-info",
+      "A simple test tool with request info",
+      { name: z.string().describe("Name to greet") },
+      async ({ name }, { requestInfo }): Promise<CallToolResult> => {
+        return { content: [{ type: "text", text: `Hello, ${name}!` }, { type: "text", text: `${JSON.stringify(requestInfo)}` }] };
+      }
+    );
+
+    const toolCallMessage: JSONRPCMessage = {
+      jsonrpc: "2.0",
+      method: "tools/call",
+      params: {
+        name: "test-request-info",
+        arguments: {
+          name: "Test User",
+        },
+      },
+      id: "call-1",
+    };
+
+    const response = await sendSsePostRequest(baseUrl, toolCallMessage, sessionId);
+
+    expect(response.status).toBe(202);
+
+    expect(mockRes.write).toHaveBeenCalledWith(`event: endpoint\ndata: /messages?sessionId=${sessionId}\n\n`);
+
+    const expectedMessage = {
+      result: {
+        content: [
+          {
+            type: "text",
+            text: "Hello, Test User!",
+          },
+          {
+            type: "text",
+            text: JSON.stringify({
+              headers: {
+                host: `127.0.0.1:${serverPort}`,
+                connection: 'keep-alive',
+                'content-type': 'application/json',
+                accept: 'application/json, text/event-stream',
+                'accept-language': '*',
+                'sec-fetch-mode': 'cors',
+                'user-agent': 'node',
+                'accept-encoding': 'gzip, deflate',
+                'content-length': '124'
+              },
+            })
+          },
+        ],
+      },
+      jsonrpc: "2.0",
+      id: "call-1",
+    };
+    expect(mockRes.write).toHaveBeenCalledWith(`event: message\ndata: ${JSON.stringify(expectedMessage)}\n\n`);
+  });
   });
 });

src/server/sse.ts

@@ -5,6 +5,7 @@ import { JSONRPCMessage, JSONRPCMessageSchema } from "../types.js";
 import getRawBody from "raw-body";
 import contentType from "content-type";
 import { AuthInfo } from "./auth/types.js";
+import { MessageExtraInfo, RequestInfo } from "./types/types.js";
 import { URL } from 'url';
 
 const MAXIMUM_MESSAGE_SIZE = "4mb";
@@ -19,7 +20,7 @@ export class SSEServerTransport implements Transport {
   private _sessionId: string;
   onclose?: () => void;
   onerror?: (error: Error) => void;
-  onmessage?: (message: JSONRPCMessage, extra?: { authInfo?: AuthInfo }) => void;
+  onmessage?: (message: JSONRPCMessage, extra: { authInfo?: AuthInfo, requestInfo: RequestInfo }) => void;
 
   /**
    * Creates a new SSE server transport, which will direct the client to POST messages to the relative or absolute URL identified by `_endpoint`.
@@ -86,6 +87,7 @@ export class SSEServerTransport implements Transport {
       throw new Error(message);
     }
     const authInfo: AuthInfo | undefined = req.auth;
+    const requestInfo: RequestInfo = { headers: req.headers };
 
     let body: string | unknown;
     try {
@@ -105,7 +107,7 @@ export class SSEServerTransport implements Transport {
     }
 
     try {
-      await this.handleMessage(typeof body === 'string' ? JSON.parse(body) : body, { authInfo });
+      await this.handleMessage(typeof body === 'string' ? JSON.parse(body) : body, { requestInfo, authInfo });
     } catch {
       res.writeHead(400).end(`Invalid message: ${body}`);
       return;
@@ -117,7 +119,7 @@ export class SSEServerTransport implements Transport {
   /**
    * Handle a client message, regardless of how it arrived. This can be used to inform the server of messages that arrive via a means different than HTTP POST.
    */
-  async handleMessage(message: unknown, extra?: { authInfo?: AuthInfo }): Promise<void> {
+  async handleMessage(message: unknown, extra: MessageExtraInfo): Promise<void> {
     let parsedMessage: JSONRPCMessage;
     try {
       parsedMessage = JSONRPCMessageSchema.parse(message);