@modelcontextprotocol/server

MCP TypeScript SDK v2 Server by Model Context Protocol

Model Context Protocol implementation for TypeScript - Server package

Live Registry Versionv2.4.0Previous: v2.3.1Published 2026-10-23

Stability Grade

B (78/100)

90-Day Velocity

5 releases

Moderate cadence

Dependencies

2 direct

NPM manifest

License

Apache-2.0

Verified on NPM

Recommended Exact Pin: npm install @modelcontextprotocol/server@2.4.0

NPM Registry ->GitHub Repo ->

TL;DR Verdict & Quick Citation Summary (2026-10-27)Source: AgentBreakWatch Live NPM Index

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 past 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. Production teams should pin npm install @modelcontextprotocol/server@2.4.0 rather than using unpinned @latest tags.

Breaking Changes & Tool Schema Drift Analysis

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.

Watched Exports / MCP Tool Signatures:

McpServerregisterTooloutputSchemastructuredContentx-mcp-header

Before (Deprecated / Unpinned Pattern)

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
// client code read structuredContent.result

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

Frequently Asked Questions: @modelcontextprotocol/server

What is the latest version of @modelcontextprotocol/server on NPM?

As of 2026-10-27, the latest stable version of @modelcontextprotocol/server (MCP TypeScript SDK v2 Server by Model Context Protocol) on NPM is v2.4.0, published on 2026-10-23. It has shipped 5 releases in the last 90 days.

Does @modelcontextprotocol/server v2.4.0 have breaking changes or MCP schema drift risk?

@modelcontextprotocol/server currently carries a HIGH schema drift risk rating with a Stability Score of 78/100 (Grade B). 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.

How do I safely pin @modelcontextprotocol/server in production?

Avoid unpinned @latest tags in production agent configs. Pin the exact verified version using `npm install @modelcontextprotocol/server@2.4.0` and monitor McpServer, registerTool, outputSchema, structuredContent, x-mcp-header for parameter or schema changes.

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