modelcontextprotocol / modelcontextprotocol/typescript-sdk

Implement SEP-1724: Extensions

Open
#1,063 1 comment 1 reaction 0 assignees View on GitHub

Nobody has claimed this yet.

enhancement needs decision P1 pending SEP approval v2
Dominant language
TypeScript
Stars
13.4k
Forks
2.2k
Avg merge
3d 15h
Merged PRs (30d)
4

Description

This is a tracking issue for implementation of SEP-1724.

Summary

This SEP establishes a comprehensive framework for extending the Model Context Protocol through optional, composable extensions. The TypeScript SDK needs to implement support for extension identifiers in the format {vendor-prefix}/{extension-name}, capabilities advertisement for extensions, and mechanisms to enable/disable extensions (with opt-in by default). This includes updating protocol types to include extension-related fields, implementing extension discovery and negotiation during session initialization, and providing SDK APIs for developers to register and use extensions. The framework introduces three categories (Unofficial, Recommended, Official) and ensures extensions are purely additive and optional, maintaining core protocol stability.

Related Issues & PRs
  • Implementation PRs: n/a
  • Related PRs: n/a
  • Related Issues: n/a

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading SEP-1724 and then trace the TypeScript SDK's protocol types and session initialization flow. The work is done when extension identifiers, capability advertisement, discovery and negotiation, opt-in enablement, and developer registration and use APIs are supported while remaining additive and optional.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
api
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.