Free tool

MCP configuration checker

Paste a Cursor mcp.json or Claude Desktop claude_desktop_config.json and check structure locally. This is not a connection tester — it never runs commands, opens URLs, or verifies credentials.

Privacy: validation stays in your browser. Input is not stored in URLs, localStorage, cookies, or analytics payloads.
Findings separate JSON syntax errors, documented config errors, and advisory warnings.
Supported first: Cursor and Claude Desktop. Unsupported or ambiguous shapes are called out — not invented.

Client

Static validation only. Runs entirely in your browser. Config text is never sent to PlugMCP, put in the URL, or written to localStorage, cookies, or analytics.

Paste MCP config JSON

Browse the directory Setup guide

What this checks

Root shape (mcpServers), per-server modes (stdio command vs remote URL where documented), required fields and value types, suspicious mixed local/remote entries, prototype-pollution keys, and size/depth limits. Unknown fields are advisories — they do not fail the whole file.

What it never claims

It does not verify that executables exist, that filesystem paths are valid, that environment values are correct, that auth works, or that a remote endpoint is reachable.

Client docs used

Cursor
- Cursor — Model Context Protocol (MCP) (verified 2026-11-07)
- Cursor Help — MCP integrations (verified 2026-11-07)
- Project file: .cursor/mcp.json. Global file: ~/.cursor/mcp.json. Both use a top-level mcpServers object.
- STDIO field table lists type as required, but official examples often omit "type": "stdio" — flagged as advisory only.
- Remote entries use url plus optional headers and static OAuth auth. envFile is STDIO-only.
- This checker does not verify that commands exist, URLs resolve, or env values are correct.
Claude Desktop
- MCP docs — Connect to local MCP servers (Claude Desktop) (verified 2026-11-07)
- Claude Help — Custom connectors using remote MCP (verified 2026-11-07)
- macOS: ~/Library/Application Support/Claude/claude_desktop_config.json. Windows: %APPDATA%\Claude\claude_desktop_config.json. Linux: ~/.config/Claude/claude_desktop_config.json.
- Official consumer file documents stdio servers via command / args / env.
- Remote MCP for Claude (including Desktop) is configured through Connectors; connections are brokered from Anthropic infrastructure, not via a url key in claude_desktop_config.json.
- Plugin/managed shapes (transport, type: http|sse) are out of scope for this checker unless clearly documented for the consumer file.

Troubleshooting

Trailing commas and comments fail JSON — use a previewed fix or remove them.
Cursor expects mcpServers, not VS Code's servers.
Claude Desktop remotes belong in Connectors for the official path; a bare url in the consumer config file is flagged.
After editing a real file, restart the client (or reload MCP) — this tool only checks the text you paste.

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