The agent harness performance optimization system. Skills, instincts, memory, security, and research-first development for Claude Code, Codex, Opencode, Cursor and beyond.
Roast My Design System
AI design system scanner + mcp server. Scores repos 0-100, writes fix prompts. 27K+ npm downloads.
Install
One-click install
Runs locallyClaude Code (no install link, copy and run)
$
claude mcp add roast -- npx -y roast-my-design-system@latest --mcpButtons open the app on your computer and ask you to confirm before anything is added.
$
claude mcp add roast -- npx roast-my-design-system@latest --mcpmcp.json (Cursor, Claude Desktop, Windsurf)
{
"mcpServers": {
"roast": {
"command": "npx",
"args": [
"-y",
"roast-my-design-system@latest",
"--mcp"
]
}
}
}Install command taken from the project's README or registry entry. Always review code before running it.
README excerpt
Read full README on GitHub →roast-my-design-system
Find where your AI agent will invent UI.
Your AI can write the UI. This makes sure it writes your UI.
npx roast-my-design-system@latest
Run it at the root of a UI repo. One second later, a report opens. No account. No network. No telemetry. Nothing in your repo changes.
Version history is in CHANGELOG.md.
The idea
An agent copies what it finds.
It invents where the repo has no answer.
We tested this on 10 real open-source products, in 355 agent sessions, with and without this tool.
Findings each session added, counted by this tool's own rules:
| Task | Model | When | Without roast | Roast MCP and rules installed | Roast plugin with its edit hook |
|---|---|---|---|---|---|
| A new chart and a new component, 4 products, 3 runs each | Sonnet 5 | Oct 2026, roast 10.1 | 21 in 24 runs | not run | 7 in 24 runs |
| A new chart and a new component, 4 products, 3 runs each | Haiku 4.5 | Oct 2026, roast 10.1 | 72 in 24 runs | not run | 1 in 24 runs |
| Add a panel, build a dashboard, tighten a list (80 sessions) | Sonnet 5 | Sept 2026 | 7 | 9 | not run |
| A Christmas theme, 10 products | Sonnet 5 | Sept 2026 | 28 | 2 | not run |
| A new chart, 4 products, 5 runs each | Sonnet 5 | Sept 2026 | 10 in 20 runs | not run | 0 in 20 runs |
| A new chart, 4 products | Haiku 4.5 | Sept 2026 | 25 | 39 | 0 in 14 of 15 runs |
| Chart, status colour, empty state, new component | Haiku 4.5 | Sept 2026 | 42 in 16 runs | 49 in 16 runs | 3 in 51 runs |
Routine work stayed on-system with or without the tool. Work that needed something new did not.
An agent does not always call a tool when it should. In October, Sonnet called the MCP tools in 7 of 24 sessions and Haiku in 2 of 24. The edit hook runs without being asked. That is the column with the lowest numbers.
Where did the agent invent? Where the repo had nothing to copy. Dub has no chart palette. Its own charts hardcode 17 colours. Asked for a chart, Haiku hardcoded 9 more. In October, 5 of the 7 findings Sonnet left with the plugin on were chart colours on Dub. The agent kept them and wrote a comment saying the repo has no chart palette.
So the mess an agent adds is a map of the gaps in your system.
This tool draws the map.
Roast. Teach. Guard.
Roast the repo to find its real design system, the mess in it, and the gaps.
Teach the agent, through generated rules and a local MCP server.
Guard every edit, so the agent does not have to remember to ask.
ROAST what is in the repo, and what is missing
↓
TEACH rules in the agent files, answers over MCP
↓
GUARD every edit checked, the PR gated
What you get
Where will your agent have to guess?
The first thing the report says: the places where the repo has no answer yet, or "No gaps found".
- the gap, in one line
- the files that prove it
- the one move that closes it
One gap is known for certain today, because the runs found it: charts hardcoding colours in a repo with no chart palette. 43 of 126 public repos look like that. A gap joins the list when it has been measured.
Fixes you can make right now to increase the health score
The mess the agent will copy, ranked by what fixing it is worth.
- what was found
- where, with the file path
- why it matters
- what to change
- a copy button with the fix prompt for your agent
Fix, rescan, press the next button.
A score you can defend in a meeting
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