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MCP Client Config Validator

Paste your MCP client configuration JSON and validate every server entry. Catches missing commands, bad types, possible secrets, and structural issues — all in your browser.

Paste MCP Client Config JSON

Your config is never uploaded.0 chars

Validation results appear here

MCP Client Config Guide

Expected config shape

{
  "mcpServers": {
    "my-server": {
      "command": "node",
      "args": ["dist/index.js"],
      "env": {
        "API_KEY": "your-key"   // ⚠ avoid hardcoding secrets
      }
    }
  }
}

Common mistakes

❌

command not on PATH

If "node" or "python" are not found, the client silently fails. Use an absolute path if needed.

❌

args not an array

"args" must be a JSON array of strings, not a single string or object.

❌

Hardcoded secrets in env

Never put API keys or tokens directly in the config file. Load them from environment variables or a .env file.

❌

Unknown top-level fields

Fields outside "mcpServers" may be ignored or cause errors depending on the client.

Privacy: This tool runs entirely in your browser. Your config JSON is never uploaded or stored.

Frequently Asked Questions

What is an MCP client config?
An MCP client config is a JSON file that tells an AI client (like Claude Desktop, Cursor, or Windsurf) which MCP servers to start and how. The core structure is a "mcpServers" object mapping server names to their launch configurations — command, args, and env.
What must every server entry contain?
"command" is required — it is the executable to run (e.g. node, python, npx). "args" is an array of command-line arguments and is optional but common. "env" is an optional key-value map of environment variables.
Why does this validator warn about secrets in env?
Env keys like API_KEY, TOKEN, or PASSWORD with non-empty values suggest you may be hardcoding secrets. Hardcoded secrets are dangerous if the config file is committed to version control. Use a .env file and reference it from your server code instead.
Does config format differ between Claude Desktop and Cursor?
Yes. The mcpServers structure is common, but file locations differ. Claude Desktop uses ~/Library/Application Support/Claude/claude_desktop_config.json on macOS. Cursor and Windsurf use their own paths. This validator checks the structural validity of the config object itself — always check your client's docs for exact file location.
Is my config uploaded anywhere?
No. Validation runs entirely in your browser. Your config JSON is never sent to any server.

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