Free · no signup · browser-local

MCP JSON Config Validator with Client-Specific Field Checks

Check MCP JSON syntax, transport fields and supported client structure. Inspect precise issue paths and distinguish unsupported options from server connection tests.

Browse all tools →

Local document tools · no commands run · no endpoint requests

Inspect your MCP document

Source configurationSource clientConfiguration · strict JSON

{
  "mcpServers": {
    "local-example": {
      "command": "node",
      "args": [
        "/absolute/path/to/server.js"
      ],
      "env": {
        "MODE": "read-only"
      }
    }
  }
}

Import JSON file

Supported scope

Strict JSON only: 100 KB, depth 20, 5,000 nodes and 1–50 servers. stdio: command, args, env. Remote: url and string headers. Desktop uses local mcpServers; Cursor uses mcpServers and URL negotiation; VS Code uses servers with explicit type stdio/http.

Unknown fields (inputs, auth/oauth, envFile, cwd, sandbox, SSE type and others) block output. They may be valid client features. Cross-client variable expressions and numeric/null env values are blocked when semantics cannot be preserved. No connection or authentication is verified.

Conversion and merge exports retain your values and may contain credentials. Review them before sharing. The diff report masks values by default.

Official references checked 2026-11-03Claude Desktop · local MCP ↗Cursor · MCP ↗VS Code · MCP configuration ↗

Validation report

mcp-validation-report.json

Matches the supported document subset

1 server entries · connection and authentication not tested

{
  "format": "mcp-validation/v1",
  "scope": "document-only; no commands, connections or authentication tested",
  "valid": true,
  "client": "desktop",
  "serverCount": 1,
  "issues": [],
  "warnings": []
}

Getting started

Choose the intended client, paste strict JSON and inspect missing fields, mixed transports and unsupported options.

Before you use the result

Checks cover this tool’s documented subset, not every client feature or server compatibility. Unsupported fields can be valid in your client.

Try an example

Paste a VS Code entry missing type to see a transport issue at its JSON path.

How it works

JSON is parsed locally with byte, depth and node limits; field rules follow the selected client and no commands or requests run.

Frequently asked questions

Check MCP JSON syntax and supported client semantics, with precise paths for issues.

How do I use MCP Config Validator?

Choose the intended client, paste strict JSON and inspect missing fields, mixed transports and unsupported options.

Does this tool upload my data?

Inputs and files are processed in your browser. Page-view analytics do not contain your tool input.

What should I check before using the result?