# MCP TypeScript SDK v2 Server (@modelcontextprotocol/server) - AgentBreakWatch Reference

> TL;DR Verdict: MCP TypeScript SDK v2 Server (`@modelcontextprotocol/server`) is currently at v2.4.0 on NPM (published 2026-10-23), with a 90-day Stability Score of 78/100 (B) and HIGH schema drift risk across 5 releases in the last 90 days. v2 split of @modelcontextprotocol/sdk. 2.4.0 rejects x-mcp-header on number parameters (error -32020, per the 2026-07-28 spec), stops wrapping outputSchema results from z.object().meta({ id }) in { result } on 2025-11-25 connections, and its bundled Ajv rejects $id or $ref values with an invalid URI scheme.

## Live Telemetry Metadata
- Canonical Page: https://agentbreakwatch.com/p/mcp-server-ts-v2
- Category Hub: https://agentbreakwatch.com/c/agent-sdks (AI Agent SDKs & Frameworks Breaking-Change Index)
- Package Name: `@modelcontextprotocol/server`
- Registry: NPM (https://www.npmjs.com/package/@modelcontextprotocol/server)
- GitHub Repository: https://github.com/modelcontextprotocol/typescript-sdk
- Vendor: Model Context Protocol
- Latest Live Version: v2.4.0
- Published Date: 2026-10-23T18:20:13.773Z
- 90-Day Release Count: 5
- Direct Dependencies: 2
- License: Apache-2.0
- Stability Score: 78/100 (Grade B)
- Schema Drift Risk: HIGH
- Recommended Exact Pin Command: `npm install @modelcontextprotocol/server@2.4.0`
- Watched Symbols / MCP Tools: McpServer, registerTool, outputSchema, structuredContent, x-mcp-header
- Snapshot Timestamp: 2026-10-27T13:07:44.092Z

## Breaking Change & Schema Drift Summary
v2 split of @modelcontextprotocol/sdk. 2.4.0 rejects x-mcp-header on number parameters (error -32020, per the 2026-07-28 spec), stops wrapping outputSchema results from z.object().meta({ id }) in { result } on 2025-11-25 connections, and its bundled Ajv rejects $id or $ref values with an invalid URI scheme.

## Migration Diff: Before (Deprecated / Unpinned Pattern)
```
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
// client code read structuredContent.result
```

## Migration Diff: After (Verified v2.4.0 Pattern)
```
import { McpServer } from "@modelcontextprotocol/server";
// on 2025-11-25 connections read structuredContent directly
// use z.int() for any parameter annotated with x-mcp-header
```

## Recent Verified Releases
- v2.4.0 (published 2026-10-23) [LATEST]
- v2.3.1 (published 2026-10-05)
- v2.3.0 (published 2026-10-02)
- v2.2.0 (published 2026-09-28)
- v2.1.0 (published 2026-09-23)
- v2.0.0 (published 2026-07-27)