Windsurf VAT Validator MCP validate_vat

How to: Windsurf VAT Validator MCP validate_vat

client:Windsurf transport:streamable-http tool:validate_vat

Add VAT Validator MCP to Windsurf

01
Open ~/.codeium/windsurf/mcp_config.json and merge this in. Keep any servers already there.

{
  "mcpServers": {
    "vat-validator-mcp": {
      "serverUrl": "https://vat-validator-mcp-production.up.railway.app"
    }
  }
}

02
Save the file and restart Windsurf.
03
Ask for something validate_vat does. Windsurf lists the server's tools on connect and calls validate_vat itself — you do not invoke it by name.
04
If nothing happens, check the server is running and that VAT Validator MCP's identifier in your config matches the one above exactly.

Global only — Windsurf has no per-project MCP config. Refresh Cascade after saving. Windsurf docs

Set these first

VAT Validator MCP will not start until these are set, so validate_vat never becomes available.

ANTHROPIC_API_KEY
HMRC_CLIENT_ID
HMRC_CLIENT_SECRET

Same tool, other clients

This list was read from the server itself, by connecting to it and calling tools/list on 24 September 2026. It is what the server actually exposes, not what its listing claims.

Mutating and Read-only are read off each tool's name, not its schema — a hint, not a guarantee. The registry stores tool names only; connect the server for its live schemas.

VAT Validator MCP MCP server