MCP Overview

The DNA MCP server is a standalone process that exposes DNA's findings as structured data to an MCP client (Claude Code, Cursor, Windsurf). It is independent of the PTB MCP server — no shared code, no shared process.

What is MCP?

MCP (Model Context Protocol) is an open standard that lets AI IDEs call external tools during a conversation. When dna mcp is connected, your AI assistant gains five purpose-built tools that make it conformance-aware — without you prompting it.

Why use MCP instead of the CLI

Without MCP:

terminal: dna check
IDE: "here are the violations, please fix..."
terminal: dna inventory
IDE: "ok here are the components..."

With MCP, the AI calls these tools on its own initiative:

you: "add a hover state to the Button"
AI: [calls dna_check → finds the change introduces a raw hex color]
AI: "I noticed this introduces rgba(182,141,66,0.1) — I'll use var(--brand) instead."

The five tools

Tool	What it does
`dna_check`	Run conformance and return structured findings — rule, severity, file, line, value, hint
`dna_resolve`	Reverse-lookup a raw value → identity token, before the literal gets written
`dna_inventory`	Return the component library as structured data — name, props, use-when, path
`dna_similar`	Structural duplication findings, tagged `rebuild` or `clone`, with scores
`dna_start_preview`	Preview what `dna start` would extract, without writing anything

All five tools are detector-only — they never write source, config, or anything outside .dna/. The AI uses the findings to make its own edits with its own tools.

Cooperation convention

When dna start runs on a project, it auto-writes a short instruction block into that project's CLAUDE.md / AGENTS.md:

Before creating a new component, call dna_inventory and dna_similar.
Before writing a raw value pulled from a design/frame, call dna_resolve — author with the token instead of a literal.
After editing a design-relevant file, call dna_check.

This means a coding agent picks up the convention automatically on its first read of the project instructions — no manual step from the human. The pre-commit hook (dna hook install) is the real backstop; the MCP convention is cooperative enforcement on top.

Next steps

See MCP Setup for installation instructions and IDE-specific configs, and Tools Reference for detailed tool schemas.