MCP Client Config Doctor: Local Config & Error Diagnosis
MCP Config DoctorLOCAL-FIRST

LOCAL MCP CONFIG CHECK

Check Your MCP Config Before Debugging the Server

Check Codex TOML, Gemini CLI JSON, or VS Code JSONC in your browser. Your pasted text is not uploaded.

  • Syntax and config shape
  • Client-specific config shape
  • Secret and env risks
Check my config
Runs locally in this tab

Your config text, names, paths and values stay local. Analytics receives only a fixed route and coarse allowlisted interaction or result categories.

01 / INPUT

Check an MCP client config

Browser memory only

Paste a config or run the safe example in one click.

02 / REPORT

Diagnostic findings

READY TO TRY

See a real result before pasting anything

Use “Try a safe example” to run a sanitized config and preview the redacted report. Runtime reachability is never inferred from configuration text.

RULE SOURCE

Manifest status

Embedded safe baseline

Bundled rules only; no remote manifest is requested.

BOUNDARY

Config vs. runtime

  • Syntax and shape only.
  • Runtime remains untested.
  • Verify in your client.

Direct answer

MCP Client Config Doctor checks supported JSON, JSONC, TOML, or .env configuration locally in the browser. It separates browser-verified config evidence from checks that require a local CLI or remote investigation.

Who this is for

  • Developers blocked after adding an MCP server in Codex, Gemini CLI, or VS Code.
  • People comparing a config copied between clients.
  • Support or DevRel workflows that need a redacted issue starter.

Who this is not for

  • A live MCP server monitor or protocol Inspector.
  • A tool that reads your files, PATH, environment, or processes.
  • A replacement for official client documentation or manual review.

Supported tasks

  • Select a target client or use format auto-detection for clearly recognized input.
  • Parse supported JSON, JSONC, TOML, or .env input.
  • Check supported client-specific shape, env/secret, and transport fields.
  • Copy a redacted diagnosis report or safe draft when the result allows it.

How it works

  1. Try the sanitized example or select a client-specific page.
  2. Paste only configuration you are authorized to handle.
  3. Run the local diagnosis.
  4. Read the controlled finding category, limitation, and recommended next step.
  5. Review the redacted report before copying; use Clear when finished.

Limitations

The Web phase cannot check PATH, binaries, process execution, stdio, handshake, OAuth, remote availability, TLS, SSE frames, or live health. No finding means no supported rule-proven issue was found, not that the configuration or server is correct. Clear removes active app state but cannot control OS clipboard, browser history, or memory.

Diagnosis levels

  • VERIFIED_IN_BROWSER: controlled static evidence from current input.
  • NEEDS_LOCAL_CLI_CHECK: PATH, binary, process, env existence, stdio, or local startup needs local tooling.
  • NEEDS_REMOTE_SERVER_INVESTIGATION: remote transport, server, OAuth, SSE, or protocol behavior needs external investigation.

Safe Patch boundary

Only a fixture-proven deterministic structural finding may produce “Copy redacted draft.” It does not write files, execute commands, or apply configuration. Unsupported, ambiguous, lossy, stale, or runtime-only cases require manual review.

Email support boundary

Use “Copy redacted report,” review the text, and email only the minimum redacted details needed for support. Never send raw configuration, logs, secrets, tokens, credentials, or private paths.

Client rules and examples

  • Shared JSON/TOML parser profiles and dynamic server-key generalization.
  • Client-specific pages flag supported roots that belong to another client; ambiguous input requires manual review.
  • Env/secret scan shows category and generalized location, not values.
  • Use sanitized fixtures to explore states without sensitive material.

FAQ

What does MCP Client Config Doctor check?

It checks supported, rule-based conditions in pasted MCP client configuration. It does not accept logs or run the client or server.

Does it test whether my MCP server is healthy?

No. This browser-local check cannot verify live server health, process state, or handshake behavior.

Does it upload my config?

The diagnostic runs locally with no input-bearing request to the application server. Sanitize input and review the Privacy Notice for hosting and browser limits.

Does Safe Patch apply changes?

No. It is a redacted draft to review and copy manually.

Is this affiliated with Codex, Gemini CLI, or VS Code?

No affiliation or endorsement is claimed. Client names describe supported configuration scope.

Key facts

  • MCP Client Config Doctor is a browser-local tool for supported MCP client configuration checks.
  • It analyzes configuration text only; it does not accept logs or receive runtime access.
  • Findings include a diagnosis level and controlled structural evidence where supported.
  • Redacted drafts and support reports require human review before use or sharing.
  • The current public service is free to use and has no account or payment flow.
  • Official-source review: 2026-07-24 UTC; revalidate after client or documentation updates.

Cause tree

  1. Syntax: malformed input stops.
  2. Structure: supported client fields only.
  3. Runtime: test in the client.

Positive fixture

A sanitized JSONC object with a documented mcpServers map, string command, string-array args, and placeholder-only environment references.

Negative fixture

Malformed JSON, an unsupported root, or copied cross-client fields must return parse error or MANUAL REVIEW without reproducing the pasted text.

Official sources

NEED MORE HELP?

Email a redacted support request

Use “Copy redacted report,” review the text, then email support@mcpconfigdoctor.online. Include the affected client and what you expected. Do not send raw configuration, logs, secrets, tokens, credentials, or private paths.