---
title: "MCP Config Validator – Check mcp.json and config.toml – Display"
description: "Check an MCP config for Claude Desktop, Claude Code, Cursor, VS Code or Codex. Find syntax errors, wrong fields and API keys. Nothing leaves your browser."
---

# MCP config validator

Paste an MCP server config to check it before your agent client reads it. The validator finds syntax errors, fields in the wrong place and API keys written in the file. Your config does not leave your browser.

Open the tool: https://display.dev/tools/mcp-config-validator

## How to use the MCP config validator

1. Paste your MCP config into the source box, or drop the .json or .toml file on it. To see how the tool works, select Load an example.
2. Select your client. Auto reads TOML as Codex, a "servers" key as VS Code, and "mcpServers" with the rules that all these clients share.
3. Read the report. Fix items stop the client from reading the server. Check items can cause errors or expose a key.
4. Fix the config in your editor and paste it again. The report changes while you type.

## Limits

- The validator checks syntax and the shape that each client documents. It does not start a server or check that a command or URL works.
- The rules come from the documentation of each client, as read on 14 October 2026. When a client adds a field, the report can show it as unknown.
- For TOML, the tool reads the parts that MCP server tables use. It does not read arrays of tables or dates.
- The key check finds common token formats and fields with names such as KEY, TOKEN or SECRET. When it finds nothing, the file can still contain a secret.
- This tool has no Get a link. Your config stays in your browser.

## MCP config validator questions

**Q: Does the validator send my config anywhere?**

No. The checks run in your browser, and the tool has no publish step, because MCP configs often contain API keys. The report shows only the first 4 characters of each likely key.

**Q: Where is my MCP config file?**

Claude Desktop uses claude_desktop_config.json in ~/Library/Application Support/Claude on macOS and in %APPDATA%\Claude on Windows. Claude Code uses .mcp.json in the project. Cursor uses .cursor/mcp.json or ~/.cursor/mcp.json. VS Code uses .vscode/mcp.json. Codex uses ~/.codex/config.toml.

**Q: Why does VS Code use "servers" and not "mcpServers"?**

The mcp.json file of VS Code keeps servers under "servers", with an "inputs" list for values that VS Code asks for. Claude Desktop, Claude Code and Cursor use "mcpServers". Codex uses [mcp_servers.name] tables in TOML.

**Q: How do I let my agent publish to Display?**

Follow the setup guide for your client in the Display docs. Agents can also use the public MCP server at https://api.display.dev/v1/public/mcp, which publishes without an account.

## Related tools

- [AGENTS.md checker](https://display.dev/tools/agents-md-checker.md): Check an AGENTS.md or CLAUDE.md file for missing commands, broken links and secrets.
- [HTML share check](https://display.dev/tools/html-share-check.md): Find missing files, local URLs and likely API keys before you send an HTML file.
- [All free tools](https://display.dev/tools.md)