Is your MCP server safe? One line in mcp.json, and your agent recovers from its own DROP TABLE

If you run an AI agent through MCP (Claude Code, Cursor, or any MCP client), your tool calls now flow through MCP servers: a filesystem server, a database server, a shell. That standardization is great. It also means a single hallucinated or prompt-injected tool call can do real, irreversible damage, and the model does not know a destructive call from a safe one until it is already making it.

So people ask: is this MCP server safe?

Here is the better question. Your agent will, eventually, send an MCP server something destructive. The question is not only whether you block it. It is whether the run survives the block.

Block it with one line. No code, no key.

Wrap any MCP server with agentx-mcp. It is a small stdio proxy: it spawns the real server, relays the MCP protocol untouched, and screens every tools/call before it runs. One line in your mcp.json: