# MCP TypeScript SDK v2 Client (@modelcontextprotocol/client) - AgentBreakWatch Reference

> TL;DR Verdict: MCP TypeScript SDK v2 Client (`@modelcontextprotocol/client`) 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. Since 2.4.0 the client does not list tools that put x-mcp-header on a number parameter, and outputSchema results built from z.object().meta({ id }) arrive unwrapped in structuredContent on 2025-11-25 connections.

## Live Telemetry Metadata
- Canonical Page: https://agentbreakwatch.com/p/mcp-client-ts-v2
- Category Hub: https://agentbreakwatch.com/c/agent-sdks (AI Agent SDKs & Frameworks Breaking-Change Index)
- Package Name: `@modelcontextprotocol/client`
- Registry: NPM (https://www.npmjs.com/package/@modelcontextprotocol/client)
- GitHub Repository: https://github.com/modelcontextprotocol/typescript-sdk
- Vendor: Model Context Protocol
- Latest Live Version: v2.4.0
- Published Date: 2026-10-23T18:21:05.614Z
- 90-Day Release Count: 5
- Direct Dependencies: 7
- License: Apache-2.0
- Stability Score: 78/100 (Grade B)
- Schema Drift Risk: HIGH
- Recommended Exact Pin Command: `npm install @modelcontextprotocol/client@2.4.0`
- Watched Symbols / MCP Tools: Client, listTools, callTool, structuredContent, OAuthClientProvider
- Snapshot Timestamp: 2026-10-27T13:07:44.092Z

## Breaking Change & Schema Drift Summary
v2 split of @modelcontextprotocol/sdk. Since 2.4.0 the client does not list tools that put x-mcp-header on a number parameter, and outputSchema results built from z.object().meta({ id }) arrive unwrapped in structuredContent on 2025-11-25 connections.

## Migration Diff: Before (Deprecated / Unpinned Pattern)
```
import { Client } from "@modelcontextprotocol/sdk/client/index.js";
const value = result.structuredContent.result;
```

## Migration Diff: After (Verified v2.4.0 Pattern)
```
import { Client } from "@modelcontextprotocol/client";
const value = result.structuredContent;
```

## 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)