# keyline

> keyline is a free, source-available MCP server that lets AI agents (Claude Code, Cursor, Codex, VS Code) design social posts, display ads, banners, flyers and video at every size from one JSON scene. It measures text fit and overflow before rendering, and renders with Skia instead of a headless browser.

- Works with Claude Code, Claude Desktop, Cursor, Codex, VS Code, Windsurf, Cline and any stdio MCP client; on macOS, Linux, Windows, Docker and GitHub Actions.
- Outputs PNG, JPEG, WebP, vector PDF, GIF, animated PNG, MP4 and WebM, at every size from one master layout.
- Deterministic: no model generates pixels; the same scene always renders the same design.
- In a benchmark (Claude Opus 5, 5 runs each, all correct) an agent used 2× fewer tokens making the same card than with HTML + headless Chrome, and 5× fewer than with Playwright MCP.
- An alternative to Puppeteer or Playwright HTML-to-image screenshots, hosted image APIs like Bannerbear or Placid, and the Canva or Figma APIs, for agents.
- Free and source-available under PolyForm Shield 1.0.0.

## Install

- Claude Code: `/plugin marketplace add keyline-dev/keyline`, then `/plugin install keyline@keyline`
- Cursor: install the binary (`brew install keyline-dev/tap/keyline-mcp`, or a download from https://github.com/keyline-dev/keyline/releases/latest), then add `{ "mcpServers": { "keyline": { "command": "keyline-mcp" } } }` to `~/.cursor/mcp.json`
- Every other client: [Install](https://keyline.dev/docs/install/index.md)

## Docs

- [Install](https://keyline.dev/docs/install/index.md): Install keyline for Claude Code, Claude Desktop, Codex, Cursor, VS Code and any MCP client, or run it in CI.
- [Concepts](https://keyline.dev/docs/index.md): How keyline works: scenes, sizes, layout, checks and renders, the ideas behind the design engine for AI agents.
- [Scene format](https://keyline.dev/docs/scene/index.md): The keyline scene format: every layer, field, default and unit, from layout and text to motion and video.
- [Tools and replies](https://keyline.dev/docs/tools/index.md): keyline's MCP tools, their replies and problem lines, output formats, server flags and rendering without an agent.

## Optional

- [Benchmark: keyline vs a headless browser](https://keyline.dev/benchmark/index.md): The same model makes the same images with keyline, HTML + headless Chrome and Playwright MCP: method, every run, tokens, turns and time.
- [All docs in one file](https://keyline.dev/llms-full.txt)
- [Source](https://github.com/keyline-dev/keyline)