Pixellint

What Pixellint MCP server does

The Pixellint MCP server brings Pixellint's spec-first validation engine into agent workflows. It checks URL-like tracking artifacts, postbacks, and server-side conversion API payloads against the core rulepack and applicable vendor rulepacks. Findings identify the rule, severity, evidence level, source document, suggested fix, and supporting documentation when available.

The server is intended for quality assurance and debugging of measurement implementations. It can identify issues such as missing vendor parameters, invalid event names, incorrectly formatted timestamps, absent purchase values or currencies, and un-hashed personal information in supported payloads. The underlying validator also supports request captures that combine an endpoint, method, headers, query fields, and body.

How it works

Install pixellint-mcp with Cargo and start it as an MCP process over standard input and output. An MCP client sends an artifact and validation options to the server; the server runs the local Pixellint engine and returns structured results. It does not upload artifacts, and the project states that no hosted MCP service is available at pixellint.org.

The validation tool accepts an artifact_kind, the artifact content, and optional vendor and rulepack controls. Callers can provide a claimed vendor, indicate whether macros are expanded, select rulepacks, or exclude selected rulepacks. Responses contain findings, detected vendors, and a severity summary, allowing an agent to act on results without parsing terminal text.

Setup and configuration

Install the server with:

cargo install pixellint-mcp

Configure the installed executable in an MCP client as a stdio server. The README does not specify environment variables or a hosted endpoint, so operation is local to the process started by the client. The MCP Registry name is mcp-name: io.github.aleksUIX/pixellint.

The broader Pixellint project also provides a separate CLI through cargo install pixellint, an npm package, and a browser playground. Those installation paths are not required to run the Pixellint MCP server.

Tools and capabilities

The server exposes three tools:

• list_rulepacks returns available validation rulepacks.
• list_vendors lists vendors and can filter by category or by a single host.
• validate_artifact validates an artifact using its kind, content, and optional vendor, expansion-state, rulepack, and exclusion settings.

The validator distinguishes artifact types such as URLs, postbacks, JSON payloads, VAST tracking URLs, and complete HTTP request captures where the corresponding kind is supplied. VAST input means an extracted tracking URL rather than a full VAST XML document. The server can therefore fit agent workflows that receive already-extracted artifacts from another parser.

Limitations and notes

Pixellint MCP server does not parse VAST, HTML, or GTM documents itself; callers must provide the relevant artifact or extracted URL. It communicates over stdio rather than a hosted MCP endpoint. The README documents no client-specific setup, authentication flow, or environment variables.

Validation behavior depends on the selected artifact kind and rulepacks. Vendor rules run when the artifact matches the relevant vendor conditions, while the core rules apply to URL-like artifacts. For sensitive data handling, the project notes that playground artifacts may be stored; that browser-playground policy does not describe storage by the local MCP process.