modelcontextprotocol / modelcontextprotocol/inspector

Evaluate SDK middleware for protocol/tracing

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enhancement v2
Dominant language
TypeScript
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Avg merge
6h 17m
Merged PRs (30d)
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Description

Context

TypeScript SDK PR #1406 adds message middleware support:
https://github.com/modelcontextprotocol/typescript-sdk/pull/1406

This adds sendMiddleware and receiveMiddleware options to Protocol, allowing transformation of JSON-RPC messages before sending and after receiving.

Potential Uses in Inspector V2

Use Case How Middleware Helps
Protocol capture receiveMiddleware could capture all messages for Protocol page without modifying client logic
Request tracing sendMiddleware could inject trace IDs for parent-child correlation
Protocol extensions Add custom capabilities to initialize (e.g., inspector metadata)
Plugin architecture Plugins could register middleware to intercept/modify messages
Debugging Inject timestamps, add debugging headers

Action Items

  • Monitor PR #1406 for merge
  • When merged, evaluate integration into McpContext.tsx
  • Consider for request trace model (linking tool calls to sampling requests)
  • Evaluate for plugin hooks in client features PR

Related

  • #1022 (Mantine UI) - current McpContext uses direct SDK connection
  • #1011 (client features UX spec) - request trace model spec
  • #983 (data spec) - history/logging architecture

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

Review TypeScript SDK PR #1406 for the sendMiddleware and receiveMiddleware APIs, then inspect the current connection handling in McpContext.tsx. Compare the middleware options with the request trace model in #1011 and the history/logging architecture in #983. Done means documenting whether Inspector V2 should integrate middleware for capture, tracing, protocol extensions, or plugin hooks.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
devtools
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Quiet
Clarity
Needs clarification
Newbie friendliness
35/100

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