MCP 2026 Check

Protocol revision 2026-07-28

Make every MCP request stand alone.

Paste HTTP headers and JSON-RPC messages. Detect missing per-request metadata, version and method mismatches, obsolete initialization, session IDs and removed RPCs before a stateless rollout.

Request trace

Migration report

Why this exists

The handshake moved into each request.

MCP 2026-07-28 is a major wire-level change. A request now declares its protocol version and client capabilities in params._meta. HTTP requests repeat the negotiated version in MCP-Protocol-Version, while MCP-Method makes routing and inspection explicit.

This checker treats a pasted trace as a migration artifact. It validates JSON-RPC basics, required request metadata, header/body agreement, server/discover, and common stateful leftovers.

Checks included

  • Required 2026-07-28 protocol version and client capabilities on every request.
  • Optional client identity shape with name and version.
  • HTTP protocol and method agreement with JSON-RPC.
  • Legacy initialize, initialized, session and resumability residue.
  • Removed ping, logging level and resource subscription methods.
  • Valid JSON-RPC request and response envelopes.

This independent static tool is not an official conformance suite and cannot test authentication, authorization, transport timing or server behavior.

Migration sequence

Move without sticky state.

  1. Support discovery. Implement server/discover with supported versions and server capabilities.
  2. Read request metadata. Validate protocol version and client capabilities independently on every call.
  3. Align HTTP headers. Reject header/body mismatches with the standard structured error.
  4. Remove session assumptions. Stop requiring initialization, session IDs, standalone GET and resume cursors.
  5. Test fallback. Keep an intentional legacy path while SDK adoption catches up.

Focused guides

Debug the exact migration edge.

2026 migration guide

A practical checklist from initialize sessions to stateless requests.

Open guide →

server/discover example

Request, response and error shapes for version discovery.

See example →

FAQ

Before deployment.

Must clients call server/discover first?

No. Servers implement discovery, while clients can invoke another RPC directly when they know the target version.

Where do capabilities go now?

In params._meta.io.modelcontextprotocol/clientCapabilities on every request, including an empty object when no optional capability applies.

Can I keep Mcp-Session-Id?

Not for the 2026-07-28 stateless profile. Maintain a separate negotiated legacy path if older clients still need sessions.

What does error -32020 mean?

It identifies a required HTTP header mismatch or malformed header.

PURPOSE & METHODOLOGY

A focused tool, with the context to use it well

MCP 2026 Check was created to help developers convert, validate, and understand MCP client configuration files. It is intended for developers configuring Model Context Protocol servers for Claude, Cursor, VS Code, Codex, and Gemini. The tool is free, requires no account, and is paired with original explanations so you can understand the result rather than copy an unexplained output.

How to use the result

Start with a sample or a non-sensitive copy of your data, run the check, and review every finding before changing a production project. Every converter and guide is tested against representative configuration examples. Explanations identify client-specific differences instead of hiding them behind a generic conversion button. Specifications and software evolve, so confirm high-impact decisions against the linked primary documentation.

Privacy and limitations

MCP configuration text is processed in your browser wherever the tool page states that local processing is used. Avoid entering passwords, access tokens, personal data, or confidential material. Automated output may be incomplete because it cannot know your entire deployment, threat model, or organizational policy.

Independent and transparent

This is an independent developer resource, not an official certification service. Source code and issue tracking are available on GitHub. Read more about the project, review the privacy policy, or report an error.