refactor: @modelcontextprotocol/sdk -> @modelcontextprotocol/server

.changeset/switch-mcp-server-v2.md

@@ -0,0 +1,5 @@
+---
+"incur": patch
+---
+
+Replaced `@modelcontextprotocol/sdk` with `@modelcontextprotocol/server` (v2), reducing dependency count by 74 packages.

TODO.md

@@ -0,0 +1,3 @@
+# TODO
+
+- [ ] Drop `@cfworker/json-schema` dependency once `@modelcontextprotocol/server` publishes a release after `2.0.0-alpha.2` — fix was merged in [typescript-sdk#1843](https://github.com/modelcontextprotocol/typescript-sdk/pull/1843)

package.json

@@ -46,7 +46,8 @@
     "SKILL.md"
   ],
   "dependencies": {
-    "@modelcontextprotocol/sdk": "^1.27.1",
+    "@cfworker/json-schema": "^4.1.1",
+    "@modelcontextprotocol/server": "^2.0.0-alpha.2",
     "@readme/openapi-parser": "^6.0.0",
     "@toon-format/toon": "^2.1.0",
     "tokenx": "^1.3.0",

src/Cli.ts

@@ -2,7 +2,7 @@ import * as fs from 'node:fs/promises'
 import * as os from 'node:os'
 import * as path from 'node:path'
 import { estimateTokenCount, sliceByTokens } from 'tokenx'
-import type { z } from 'zod'
+import { z } from 'zod'
 
 import * as Completions from './Completions.js'
 import type { FieldError } from './Errors.js'
@@ -1539,9 +1539,8 @@ function createMcpHttpHandler(name: string, version: string) {
     },
   ): Promise<Response> => {
     if (!transport) {
-      const { McpServer } = await import('@modelcontextprotocol/sdk/server/mcp.js')
-      const { WebStandardStreamableHTTPServerTransport } =
-        await import('@modelcontextprotocol/sdk/server/webStandardStreamableHttp.js')
+      const { McpServer, WebStandardStreamableHTTPServerTransport } =
+        await import('@modelcontextprotocol/server')
 
       const server = new McpServer({ name, version })
 
@@ -1556,7 +1555,7 @@ function createMcpHttpHandler(name: string, version: string) {
           tool.name,
           {
             ...(tool.description ? { description: tool.description } : undefined),
-            ...(hasInput ? { inputSchema: mergedShape } : undefined),
+            ...(hasInput ? { inputSchema: z.object(mergedShape) } : undefined),
           },
           async (...callArgs: any[]) => {
             const params = hasInput ? (callArgs[0] as Record<string, unknown>) : {}

src/Mcp.test.ts

@@ -103,6 +103,22 @@ describe('Mcp', () => {
     expect(res.result.capabilities.tools).toBeDefined()
   })
 
+  test('initialize with 2025-03-26 protocol version', async () => {
+    const [res] = await mcpSession(createTestCommands(), [
+      {
+        id: 1,
+        method: 'initialize',
+        params: {
+          protocolVersion: '2025-03-26',
+          capabilities: {},
+          clientInfo: { name: 'test-client', version: '1.0.0' },
+        },
+      },
+    ])
+    expect(res.result.serverInfo).toEqual({ name: 'test-cli', version: '1.0.0' })
+    expect(res.result.capabilities.tools).toBeDefined()
+  })
+
   test('tools/list returns all leaf commands as tools', async () => {
     const [, res] = await mcpSession(createTestCommands(), [
       { id: 1, method: 'initialize', params: initParams },

src/Mcp.ts

@@ -1,7 +1,6 @@
-import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
-import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'
+import { McpServer, StdioServerTransport } from '@modelcontextprotocol/server'
 import type { Readable, Writable } from 'node:stream'
-import type { z } from 'zod'
+import { z } from 'zod'
 
 import * as Command from './internal/command.js'
 import type { Handler as MiddlewareHandler } from './middleware.js'
@@ -27,7 +26,7 @@ export async function serve(
       tool.name,
       {
         ...(tool.description ? { description: tool.description } : undefined),
-        ...(hasInput ? { inputSchema: mergedShape } : undefined),
+        ...(hasInput ? { inputSchema: z.object(mergedShape) } : undefined),
         ...(tool.outputSchema ? { outputSchema: tool.outputSchema } : undefined),
       } as never,
       async (...callArgs: any[]) => {
@@ -36,6 +35,7 @@ export async function serve(
         const extra = hasInput ? callArgs[1] : callArgs[0]
         return callTool(tool, params, {
           extra,
+          sendNotification: (n) => server.server.notification(n),
           name,
           version,
           middlewares: options.middlewares,
@@ -76,9 +76,9 @@ export async function callTool(
   params: Record<string, unknown>,
   options: {
     extra?: {
-      _meta?: { progressToken?: string | number }
-      sendNotification?: (n: any) => Promise<void>
+      mcpReq?: { _meta?: { progressToken?: string | number } }
     }
+    sendNotification?: (n: ProgressNotification) => Promise<void>
     name?: string | undefined
     version?: string | undefined
     middlewares?: MiddlewareHandler[] | undefined
@@ -114,13 +114,13 @@ export async function callTool(
   if ('stream' in result) {
     // Streaming: send progress notifications per chunk, then return buffered result
     const chunks: unknown[] = []
-    const progressToken = options.extra?._meta?.progressToken
+    const progressToken = options.extra?.mcpReq?._meta?.progressToken
     let i = 0
     try {
       for await (const chunk of result.stream) {
         chunks.push(chunk)
-        if (progressToken !== undefined && options.extra?.sendNotification)
-          await options.extra.sendNotification({
+        if (progressToken !== undefined && options.sendNotification)
+          await options.sendNotification({
             method: 'notifications/progress' as const,
             params: { progressToken, progress: ++i, message: JSON.stringify(chunk) },
           })
@@ -149,6 +149,12 @@ export async function callTool(
   }
 }
 
+/** @internal A progress notification sent during streaming tool calls. */
+type ProgressNotification = {
+  method: 'notifications/progress'
+  params: { progressToken: string | number; progress: number; message: string }
+}
+
 /** @internal A resolved tool entry from the command tree. */
 export type ToolEntry = {
   name: string

src/e2e.test.ts

@@ -2848,6 +2848,47 @@ describe('fetch api', () => {
       `)
     })
 
+    test('tools/call with no-args command', async () => {
+      const cli = createApp()
+      const sessionId = await initSession(cli)
+      const res = await mcpRequest(
+        cli,
+        {
+          jsonrpc: '2.0',
+          id: 6,
+          method: 'tools/call',
+          params: { name: 'ping', arguments: {} },
+        },
+        sessionId,
+      )
+      expect(res.status).toBe(200)
+      const body = await res.json()
+      expect(JSON.parse(body.result.content[0].text)).toMatchInlineSnapshot(`
+        {
+          "pong": true,
+        }
+      `)
+    })
+
+    test('tools/call with streaming command', async () => {
+      const cli = createApp()
+      const sessionId = await initSession(cli)
+      const res = await mcpRequest(
+        cli,
+        {
+          jsonrpc: '2.0',
+          id: 7,
+          method: 'tools/call',
+          params: { name: 'stream', arguments: {} },
+        },
+        sessionId,
+      )
+      expect(res.status).toBe(200)
+      const body = await res.json()
+      const chunks = JSON.parse(body.result.content[0].text)
+      expect(chunks).toEqual([{ content: 'hello' }, { content: 'world' }])
+    })
+
     test('non-/mcp paths still work alongside MCP', async () => {
       const cli = createApp()
       // Initialize MCP first