Passthrough removal part 2: Achieve 0 passthrough types.

src/client/index.ts

@@ -7,7 +7,6 @@ import {
     type ClientNotification,
     type ClientRequest,
     type ClientResult,
-    type CompatibilityCallToolResultSchema,
     type CompleteRequest,
     CompleteResultSchema,
     EmptyResultSchema,
@@ -27,18 +26,18 @@ import {
     ListToolsResultSchema,
     type LoggingLevel,
     McpError,
-    type Notification,
     type ReadResourceRequest,
     ReadResourceResultSchema,
-    type Request,
-    type Result,
     type ServerCapabilities,
     SUPPORTED_PROTOCOL_VERSIONS,
     type SubscribeRequest,
     type Tool,
     type UnsubscribeRequest,
     ElicitResultSchema,
-    ElicitRequestSchema
+    ElicitRequestSchema,
+    type RequestGeneric,
+    type NotificationGeneric,
+    type Result
 } from '../types.js';
 import { AjvJsonSchemaValidator } from '../validation/ajv-provider.js';
 import type { JsonSchemaType, JsonSchemaValidator, jsonSchemaValidator } from '../validation/types.js';
@@ -149,8 +148,8 @@ export type ClientOptions = ProtocolOptions & {
  * ```
  */
 export class Client<
-    RequestT extends Request = Request,
-    NotificationT extends Notification = Notification,
+    RequestT extends RequestGeneric = RequestGeneric,
+    NotificationT extends NotificationGeneric = NotificationGeneric,
     ResultT extends Result = Result
 > extends Protocol<ClientRequest | RequestT, ClientNotification | NotificationT, ClientResult | ResultT> {
     private _serverCapabilities?: ServerCapabilities;
@@ -461,7 +460,7 @@ export class Client<
 
     async callTool(
         params: CallToolRequest['params'],
-        resultSchema: typeof CallToolResultSchema | typeof CompatibilityCallToolResultSchema = CallToolResultSchema,
+        resultSchema: typeof CallToolResultSchema = CallToolResultSchema,
         options?: RequestOptions
     ) {
         const result = await this.request({ method: 'tools/call', params }, resultSchema, options);

src/server/index.ts

@@ -20,16 +20,16 @@ import {
     LoggingLevelSchema,
     type LoggingMessageNotification,
     McpError,
-    type Notification,
-    type Request,
     type ResourceUpdatedNotification,
-    type Result,
     type ServerCapabilities,
     type ServerNotification,
     type ServerRequest,
     type ServerResult,
     SetLevelRequestSchema,
-    SUPPORTED_PROTOCOL_VERSIONS
+    SUPPORTED_PROTOCOL_VERSIONS,
+    type RequestGeneric,
+    type NotificationGeneric,
+    type Result
 } from '../types.js';
 import { AjvJsonSchemaValidator } from '../validation/ajv-provider.js';
 import type { JsonSchemaType, jsonSchemaValidator } from '../validation/types.js';
@@ -104,8 +104,8 @@ export type ServerOptions = ProtocolOptions & {
  * @deprecated Use `McpServer` instead for the high-level API. Only use `Server` for advanced use cases.
  */
 export class Server<
-    RequestT extends Request = Request,
-    NotificationT extends Notification = Notification,
+    RequestT extends RequestGeneric = RequestGeneric,
+    NotificationT extends NotificationGeneric = NotificationGeneric,
     ResultT extends Result = Result
 > extends Protocol<ServerRequest | RequestT, ServerNotification | NotificationT, ServerResult | ResultT> {
     private _clientCapabilities?: ClientCapabilities;

src/server/mcp.test.ts

@@ -4273,6 +4273,7 @@ describe('elicitInput()', () => {
 
         expect(checkAvailability).toHaveBeenCalledWith('ABC Restaurant', '2024-12-25', 2);
         expect(findAlternatives).not.toHaveBeenCalled();
+
         expect(result.content).toEqual([
             {
                 type: 'text',

src/shared/protocol.test.ts

@@ -1,5 +1,5 @@
 import { ZodType, z } from 'zod';
-import { ClientCapabilities, ErrorCode, McpError, Notification, Request, Result, ServerCapabilities } from '../types.js';
+import { ClientCapabilities, ErrorCode, McpError, NotificationGeneric, RequestGeneric, Result, ServerCapabilities } from '../types.js';
 import { Protocol, mergeCapabilities } from './protocol.js';
 import { Transport } from './transport.js';
 import { MockInstance } from 'vitest';
@@ -18,14 +18,14 @@ class MockTransport implements Transport {
 }
 
 describe('protocol tests', () => {
-    let protocol: Protocol<Request, Notification, Result>;
+    let protocol: Protocol<RequestGeneric, NotificationGeneric, Result>;
     let transport: MockTransport;
     let sendSpy: MockInstance;
 
     beforeEach(() => {
         transport = new MockTransport();
         sendSpy = vi.spyOn(transport, 'send');
-        protocol = new (class extends Protocol<Request, Notification, Result> {
+        protocol = new (class extends Protocol<RequestGeneric, NotificationGeneric, Result> {
             protected assertCapabilityForMethod(): void {}
             protected assertNotificationCapability(): void {}
             protected assertRequestHandlerCapability(): void {}
@@ -479,7 +479,7 @@ describe('protocol tests', () => {
 
         it('should NOT debounce a notification that has parameters', async () => {
             // ARRANGE
-            protocol = new (class extends Protocol<Request, Notification, Result> {
+            protocol = new (class extends Protocol<RequestGeneric, NotificationGeneric, Result> {
                 protected assertCapabilityForMethod(): void {}
                 protected assertNotificationCapability(): void {}
                 protected assertRequestHandlerCapability(): void {}
@@ -500,7 +500,7 @@ describe('protocol tests', () => {
 
         it('should NOT debounce a notification that has a relatedRequestId', async () => {
             // ARRANGE
-            protocol = new (class extends Protocol<Request, Notification, Result> {
+            protocol = new (class extends Protocol<RequestGeneric, NotificationGeneric, Result> {
                 protected assertCapabilityForMethod(): void {}
                 protected assertNotificationCapability(): void {}
                 protected assertRequestHandlerCapability(): void {}
@@ -519,7 +519,7 @@ describe('protocol tests', () => {
 
         it('should clear pending debounced notifications on connection close', async () => {
             // ARRANGE
-            protocol = new (class extends Protocol<Request, Notification, Result> {
+            protocol = new (class extends Protocol<RequestGeneric, NotificationGeneric, Result> {
                 protected assertCapabilityForMethod(): void {}
                 protected assertNotificationCapability(): void {}
                 protected assertRequestHandlerCapability(): void {}
@@ -543,7 +543,7 @@ describe('protocol tests', () => {
 
         it('should debounce multiple synchronous calls when params property is omitted', async () => {
             // ARRANGE
-            protocol = new (class extends Protocol<Request, Notification, Result> {
+            protocol = new (class extends Protocol<RequestGeneric, NotificationGeneric, Result> {
                 protected assertCapabilityForMethod(): void {}
                 protected assertNotificationCapability(): void {}
                 protected assertRequestHandlerCapability(): void {}
@@ -570,7 +570,7 @@ describe('protocol tests', () => {
 
         it('should debounce calls when params is explicitly undefined', async () => {
             // ARRANGE
-            protocol = new (class extends Protocol<Request, Notification, Result> {
+            protocol = new (class extends Protocol<RequestGeneric, NotificationGeneric, Result> {
                 protected assertCapabilityForMethod(): void {}
                 protected assertNotificationCapability(): void {}
                 protected assertRequestHandlerCapability(): void {}
@@ -595,7 +595,7 @@ describe('protocol tests', () => {
 
         it('should send non-debounced notifications immediately and multiple times', async () => {
             // ARRANGE
-            protocol = new (class extends Protocol<Request, Notification, Result> {
+            protocol = new (class extends Protocol<RequestGeneric, NotificationGeneric, Result> {
                 protected assertCapabilityForMethod(): void {}
                 protected assertNotificationCapability(): void {}
                 protected assertRequestHandlerCapability(): void {}
@@ -628,7 +628,7 @@ describe('protocol tests', () => {
 
         it('should handle sequential batches of debounced notifications correctly', async () => {
             // ARRANGE
-            protocol = new (class extends Protocol<Request, Notification, Result> {
+            protocol = new (class extends Protocol<RequestGeneric, NotificationGeneric, Result> {
                 protected assertCapabilityForMethod(): void {}
                 protected assertNotificationCapability(): void {}
                 protected assertRequestHandlerCapability(): void {}

src/shared/protocol.ts

@@ -19,11 +19,13 @@ import {
     ProgressNotificationSchema,
     Request,
     RequestId,
-    Result,
     ServerCapabilities,
     RequestMeta,
     MessageExtraInfo,
-    RequestInfo
+    RequestInfo,
+    type RequestGeneric,
+    type NotificationGeneric,
+    type Result
 } from '../types.js';
 import { Transport, TransportSendOptions } from './transport.js';
 import { AuthInfo } from '../server/auth/types.js';
@@ -171,7 +173,11 @@ type TimeoutInfo = {
  * Implements MCP protocol framing on top of a pluggable transport, including
  * features like request/response linking, notifications, and progress.
  */
-export abstract class Protocol<SendRequestT extends Request, SendNotificationT extends Notification, SendResultT extends Result> {
+export abstract class Protocol<
+    SendRequestT extends RequestGeneric,
+    SendNotificationT extends NotificationGeneric,
+    SendResultT extends Result
+> {
     private _transport?: Transport;
     private _requestMessageId = 0;
     private _requestHandlers: Map<