MCP Protocol News - July 3, 2026

Week of: July 3, 2026

Overview

The MCP ecosystem saw coordinated beta releases of both the TypeScript and Python SDKs for the upcoming July 28, 2026 specification, alongside spec clarifications and bug fixes. The TypeScript SDK shipped v2.0.0-beta.2 across all sub-packages with CommonJS/ESM dual builds and HTTP error handling improvements, while the Python SDK released its first v2 beta with full 2026-07-28 spec support.

Stories

1. MCP TypeScript SDK v2 Beta Released with Split Packages

Source: MCP TypeScript SDK Link: https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/v2.0.0-beta.1

The TypeScript SDK v2 beta introduces a major revision for the 2026-07-28 MCP spec, splitting the monolithic @modelcontextprotocol/sdk into separate @modelcontextprotocol/server and @modelcontextprotocol/client packages, with thin optional adapters for Express, Hono, Fastify, and Node's http. Developers can now install only the side they need via npm install @modelcontextprotocol/server@beta or @modelcontextprotocol/client@beta.

The API is settling but can still change before the stable release on July 28, 2026. This restructuring reduces dependency footprint for server-only or client-only implementations and aligns with the modular direction of the spec.

Impact Analysis: Server and client implementers should begin migrating to the split packages now to surface breaking changes before the stable release.

2. TypeScript SDK v2.0.0-beta.2 Ships CommonJS/ESM Dual Builds Across All Packages

Source: MCP TypeScript SDK Link: https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/%40modelcontextprotocol%2Fserver-legacy%402.0.0-beta.2

All nine TypeScript SDK packages (core, server, client, node, express, fastify, hono, server-legacy, codemod) received patch updates to ship CommonJS builds alongside ESM. Each package now emits both .mjs/.d.mts and .cjs/.d.cts via tsdown, with exports map require conditions so require('@modelcontextprotocol/...') works from Node.js. The @modelcontextprotocol/core package moved from .js/.d.ts to .mjs/.d.mts; public import paths remain unchanged.

Additionally, the @modelcontextprotocol/server package now returns HTTP 400 for MissingRequiredClientCapabilityError (-32021) produced after dispatch, aligning with the spec mandate for 400 Bad Request on this error.

Impact Analysis: Dual builds ensure compatibility with both ESM and CommonJS environments, critical for enterprise deployments still using require().

3. Python SDK v2.0.0b1 Released with Full 2026-07-28 Spec Support

Source: MCP Python SDK Link: https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.0.0b1

The Python SDK released its first v2 beta with full support for the 2026-07-28 MCP specification. Pre-releases are opt-in only — pip install mcp still resolves to the stable 1.x line. Developers must explicitly install mcp==2.0.0b1. The beta includes a full tutorial, API reference, and migration guide from v1.

The architecture is settled, though the API can still shift before the stable v2 targeted for July 28, 2026. The release notes recommend pinning an exact version during beta.

Impact Analysis: Python server authors should start testing against v2.0.0b1 to identify migration issues early, especially around the decorator API that carries over from v1.

4. MCP Specification Blog Post Announcing SDK Betas for July 28 Published

Source: MCP Specification Link: https://github.com/modelcontextprotocol/modelcontextprotocol/commit/936408a90163b24874643d58aec9481123e400f6

A blog post announcing the Python and TypeScript SDK betas for the 2026-07-28 spec was added to the specification repository. The post is developer-focused, with a compatibility section up front, runnable install and migration steps for both SDKs, links to the RC and transports posts for context, and pointers to SDK documentation sites. It also mentions upcoming Go and C# SDK betas.

Impact Analysis: The centralized announcement provides a single source of truth for developers planning their migration timeline to the July 28 spec.

5. Spec Clarifications Correct SDK Beta Blog Post Claims

Source: MCP Specification Link: https://github.com/modelcontextprotocol/modelcontextprotocol/commit/60dc69e9a9723a7bab535ade6c5c5b9695d97dfc

Several claims in the SDK betas blog post were corrected: the "resolves to a stable version" install claim was scoped to Python, Go, and C# only — TypeScript v2 packages are new package names with no stable release, so installing them is itself the beta opt-in. The corrections also note that Python and C# servers pick up the new revision on upgrade, in contrast to the TypeScript/Go transport-level opt-in, and that v2 SDK lines are new major versions with breaking changes separate from anything happening on July 28.

Impact Analysis: Developers relying on the blog post for migration guidance should review these corrections to avoid incorrect assumptions about TypeScript SDK installation behavior.

6. Spec Decouples Mcp-Param-* Header Emission from Schema TTL

Source: MCP Specification Link: https://github.com/modelcontextprotocol/modelcontextprotocol/commit/c87328cceac49aa2c95b5b948891cedebb74f96f

A specification pull request was merged to decouple Mcp-Param-* header emission from schema TTL. This change separates when parameter headers are sent from the time-to-live configuration of the schema, giving implementers more flexibility in header management.

Impact Analysis: Server authors should review their header emission logic to ensure compliance with the decoupled behavior.

7. Codemod v2.0.0-beta.2 Includes v1-to-v2 Migration Fixes

Source: MCP TypeScript SDK Link: https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/%40modelcontextprotocol%2Fcodemod%402.0.0-beta.2

The @modelcontextprotocol/codemod package received v1-to-v2 migration fixes from continued real-world migrations (codemod iterations 5). This tool helps automate the transition from the v1 SDK to the v2 split-package architecture.

Impact Analysis: Teams with large v1 codebases should leverage the updated codemod to reduce manual migration effort.

Source Links

• MCP TypeScript SDK - MCP TypeScript SDK v2 (beta)
• MCP TypeScript SDK - @modelcontextprotocol/server-legacy@2.0.0-beta.2
• MCP Python SDK - v2.0.0b1
• MCP Specification - Add blog post announcing SDK betas for 2026-07-28 (#2988)
• MCP Specification - Correct several claims in the SDK betas blog post (#2997)
• MCP Specification - Merge pull request #2972 from modelcontextprotocol/paulc/mcp-param-tt…
• MCP TypeScript SDK - @modelcontextprotocol/codemod@2.0.0-beta.2