vastlint

If you work with video ad tech, you've probably debugged a malformed VAST tag at 3am. This MCP server wraps a Rust validator that checks IAB VAST 2.0 through 4.3 against 121 spec rules. Connect Claude to vastlint.org/mcp and call validate_vast, inspect_vast, or fix_vast with structured JSON responses that include rule IDs and XPath locations. The same zero-dependency core powers bindings for Go, Erlang, and WASM, so you get consistent results whether you're validating in Claude, a bidder pipeline, or a browser. Sub-millisecond latency, Apache 2.0 licensed, and it catches the revenue-impacting errors before they hit production.