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MCPDev

MCPDev

Build, debug and migrate MCP servers and MCP Apps. Every page names the spec version it targets, and its code comes from a project that runs.
What MCP isFix an error

Start from what you are doing

Section titled “Start from what you are doing”
I want to write a serverTypeScript, Python, Java or Go, tested against both protocol generations.I want to build an MCP AppA tool that returns an interactive view, rendered by the host.My server does not startRun the exact command, keep stdout clean, check env and PATH.I have an error messagePaste the exact text the client printed and get the likely causes.I am connecting a clientGenerate the config for Claude Code, Codex, Cursor or Cherry Studio.I followed an old tutorialWhat changed since SSE, sessions and the initialize handshake.I am putting a server onlineDocker, nginx without broken streams, and OAuth.What changed in the spec?Every method and type that changed from 2025-11-25 to 2026-07-28.

How this site is written

Section titled “How this site is written”
  • One spec version per page. Pages target MCP 2026-07-28 unless they say otherwise. Older behavior only appears on migration pages and in clearly marked notes.
  • Code that runs. Snippets come from projects under examples/mcp/ in the source repository, pinned to the versions shown at the top of each page.
  • Evidence levels. E1 means summarized from official documentation; E2 means reproduced in a recorded environment; E3 means tested in a real client.

MCPDev is community documentation. It is not affiliated with the Model Context Protocol project or with the vendors of the clients it covers.