Typecheck the three test workspace packages, and fix the registerPrompt typing defect they were hiding (#2841)

Signed-off-by: Sharvil Saxena <sharvil.saxena@gmail.com>
Co-authored-by: Felix Weinberger <3823880+felixweinberger@users.noreply.github.com>

Author: sharziki

.changeset/register-prompt-context-only-overload.md

@@ -0,0 +1,5 @@
+---
+'@modelcontextprotocol/server': patch
+---
+
+`McpServer.registerPrompt()` now types the callback correctly when no `argsSchema` is given: its one parameter is the server context. Before, reading `ctx.mcpReq` there was a type error although it worked at runtime. Prompts registered with an `argsSchema` are unchanged.

packages/server/src/server/mcp.ts

@@ -1082,6 +1082,19 @@ export class McpServer {
      * );
      * ```
      */
+    registerPrompt(
+        name: string,
+        config: {
+            title?: string;
+            description?: string;
+            argsSchema?: undefined;
+            icons?: Icon[];
+            /** Determines whether this prompt retrieval needs an OAuth scope challenge. */
+            scopeChallenge?: ScopeChallengeHandler;
+            _meta?: Record<string, unknown>;
+        },
+        cb: PromptCallback
+    ): RegisteredPrompt;
     registerPrompt<Args extends StandardSchemaWithJSON>(
         name: string,
         config: {
@@ -1118,7 +1131,7 @@ export class McpServer {
             scopeChallenge?: ScopeChallengeHandler;
             _meta?: Record<string, unknown>;
         },
-        cb: PromptCallback<StandardSchemaWithJSON> | LegacyPromptCallback<ZodRawShape>
+        cb: PromptCallback | PromptCallback<StandardSchemaWithJSON> | LegacyPromptCallback<ZodRawShape>
     ): RegisteredPrompt {
         if (this._registeredPrompts[name]) {
             throw new Error(`Prompt ${name} is already registered`);

packages/server/test/server/registerPromptNoArgs.test.ts

@@ -0,0 +1,28 @@
+// Pins the types of registerPrompt() without argsSchema: the callback's one parameter is the server context.
+import type { ServerContext } from '@modelcontextprotocol/core-internal';
+import { describe, expect, expectTypeOf, test } from 'vitest';
+
+import { McpServer } from '../../src/server/mcp';
+
+describe('registerPrompt without argsSchema', () => {
+    test('types the callback parameter as the server context', () => {
+        const server = new McpServer({ name: 'test server', version: '1.0' });
+
+        server.registerPrompt('ctx-only', {}, async ctx => {
+            expectTypeOf(ctx).toEqualTypeOf<ServerContext>();
+            return { messages: [{ role: 'assistant' as const, content: { type: 'text' as const, text: String(ctx.mcpReq.id) } }] };
+        });
+
+        expect(server.server).toBeDefined();
+    });
+
+    test('still accepts a callback that ignores the context', () => {
+        const server = new McpServer({ name: 'test server', version: '1.0' });
+
+        server.registerPrompt('no-args', { description: 'takes nothing' }, async () => ({
+            messages: [{ role: 'assistant' as const, content: { type: 'text' as const, text: 'ok' } }]
+        }));
+
+        expect(server.server).toBeDefined();
+    });
+});

pnpm-lock.yaml

@@ -22,6 +22,7 @@
         "mcp"
     ],
     "scripts": {
+        "typecheck": "tsgo -p tsconfig.json --noEmit",
         "lint": "eslint src/ && prettier --ignore-path ../../.prettierignore --check .",
         "lint:fix": "eslint src/ --fix && prettier --ignore-path ../../.prettierignore --write .",
         "check": "npm run typecheck && npm run lint",
@@ -51,6 +52,7 @@
         "cors": "catalog:runtimeServerOnly",
         "express": "catalog:runtimeServerOnly",
         "tsx": "catalog:devTools",
+        "@typescript/native-preview": "catalog:devTools",
         "zod": "catalog:runtimeShared"
     }
 }

test/conformance/package.json

@@ -200,7 +200,10 @@ function createMcpServer() {
             inputSchema: fromJsonSchema<{ region?: string; level?: number }>({
                 type: 'object',
                 properties: {
-                    region: { type: 'string', description: 'mirrored into Mcp-Param-Region', 'x-mcp-header': 'Region' },
+                    region: { type: 'string', description: 'mirrored into Mcp-Param-Region', 'x-mcp-header': 'Region' } as Record<
+                        string,
+                        unknown
+                    >,
                     level: { type: 'integer', description: 'non-mirrored argument' }
                 }
             })

test/conformance/src/everythingServer.ts

@@ -13,7 +13,9 @@
                 "./node_modules/@modelcontextprotocol/core-internal/src/exports/public/index.ts"
             ],
             "@modelcontextprotocol/client": ["./node_modules/@modelcontextprotocol/client/src/index.ts"],
+            "@modelcontextprotocol/client/_shims": ["./node_modules/@modelcontextprotocol/client/src/shimsNode.ts"],
             "@modelcontextprotocol/server": ["./node_modules/@modelcontextprotocol/server/src/index.ts"],
+            "@modelcontextprotocol/server/_shims": ["./node_modules/@modelcontextprotocol/server/src/shimsNode.ts"],
             "@modelcontextprotocol/express": ["./node_modules/@modelcontextprotocol/express/src/index.ts"],
             "@modelcontextprotocol/node": ["./node_modules/@modelcontextprotocol/node/src/index.ts"],
             "@modelcontextprotocol/vitest-config": ["./node_modules/@modelcontextprotocol/vitest-config/tsconfig.json"],

test/conformance/tsconfig.json

@@ -22,6 +22,7 @@
         "mcp"
     ],
     "scripts": {
+        "typecheck": "tsgo -p tsconfig.json --noEmit",
         "lint": "eslint src/ && prettier --ignore-path ../../.prettierignore --check .",
         "lint:fix": "eslint src/ --fix && prettier --ignore-path ../../.prettierignore --write .",
         "check": "npm run typecheck && npm run lint"
@@ -32,6 +33,7 @@
         "vitest": "catalog:devTools",
         "@modelcontextprotocol/tsconfig": "workspace:^",
         "@modelcontextprotocol/vitest-config": "workspace:^",
-        "@modelcontextprotocol/eslint-config": "workspace:^"
+        "@modelcontextprotocol/eslint-config": "workspace:^",
+        "@typescript/native-preview": "catalog:devTools"
     }
 }

test/helpers/package.json

@@ -22,6 +22,7 @@
         "mcp"
     ],
     "scripts": {
+        "typecheck": "tsgo -p tsconfig.json --noEmit",
         "lint": "eslint test/ && prettier --ignore-path ../../.prettierignore --check .",
         "lint:fix": "eslint test/ --fix && prettier --ignore-path ../../.prettierignore --write .",
         "check": "npm run typecheck && npm run lint",
@@ -42,6 +43,7 @@
         "@modelcontextprotocol/tsconfig": "workspace:^",
         "@modelcontextprotocol/vitest-config": "workspace:^",
         "@valibot/to-json-schema": "catalog:devTools",
+        "@typescript/native-preview": "catalog:devTools",
         "arktype": "catalog:devTools",
         "supertest": "catalog:devTools",
         "valibot": "catalog:devTools",

test/integration/package.json

@@ -73,7 +73,8 @@ test('should initialize with matching protocol version', async () => {
  * Test: Initialize with Supported Older Protocol Version
  */
 test('should initialize with supported older protocol version', async () => {
-    const OLD_VERSION = SUPPORTED_PROTOCOL_VERSIONS[1];
+    // Index 1 is always present; `noUncheckedIndexedAccess` cannot see that.
+    const OLD_VERSION = SUPPORTED_PROTOCOL_VERSIONS[1]!;
     const clientTransport: Transport = {
         start: vi.fn().mockResolvedValue(undefined),
         close: vi.fn().mockResolvedValue(undefined),
@@ -277,7 +278,8 @@ test('should reject unsupported protocol version', async () => {
  * Test: Connect New Client to Old Supported Server Version
  */
 test('should connect new client to old, supported server version', async () => {
-    const OLD_VERSION = SUPPORTED_PROTOCOL_VERSIONS[1];
+    // Index 1 is always present; `noUncheckedIndexedAccess` cannot see that.
+    const OLD_VERSION = SUPPORTED_PROTOCOL_VERSIONS[1]!;
     const server = new Server(
         {
             name: 'test server',
@@ -725,7 +727,7 @@ test('should only allow setRequestHandler for declared capabilities', () => {
 
     // This should throw because roots listing is not a declared capability
     expect(() => {
-        client.setRequestHandler('roots/list', () => ({}));
+        client.setRequestHandler('roots/list', () => ({ roots: [] }));
     }).toThrow('Client does not support roots capability');
 });