MCP server

@devlooped/plotdown-mcp gives a model one tool, render_plot, and the host shows the chart in the conversation: an MCP App view that follows the host's theme and width, with the source a tab away and a button that copies the block as a ```plot fence.

Configure your host

The server needs Node 22.12 or later and speaks stdio by default.

Claude Desktop, in claude_desktop_config.json (Settings › Developer › Edit Config):

{
  "mcpServers": {
    "plotdown": {"command": "npx", "args": ["-y", "@devlooped/plotdown-mcp"]}
  }
}

Claude Code:

claude mcp add plotdown -- npx -y @devlooped/plotdown-mcp

VS Code, in .vscode/mcp.json (or MCP: Add Server…):

{
  "servers": {
    "plotdown": {"type": "stdio", "command": "npx", "args": ["-y", "@devlooped/plotdown-mcp"]}
  }
}

Other hosts that take a command take the same one, npx -y @devlooped/plotdown-mcp. For a host that connects to a URL, run it over Streamable HTTP:

npx -y @devlooped/plotdown-mcp --http --port 3001    # http://127.0.0.1:3001/mcp

It binds 127.0.0.1 and refuses a Host header that is not local. --host 0.0.0.0 opens it to the network with no authentication: put a proxy that adds some in front.

What the model gets


`render_plot`	Takes `plot`: the block as a JSON object, or as text (a fence around it is fine). Read-only, no network.
`plotdown://spec`	The whole format, as Markdown
`plotdown://schema`	The JSON Schema of a block
`ui://plotdown/view.html`	The view: one self-contained file, nothing loaded from the network

A block with a mistake comes back as a tool error that names the place, so the model fixes it and calls again:

Invalid plot block at $.marks[0].mark: unknown mark "pie"
Fix the value at $.marks[0].mark and call render_plot again. The format is in the resource plotdown://spec.

A host without MCP Apps gets the chart as a PNG image instead of the view, drawn on your machine, with a short summary and the block as a ```plot fence, which a chat that renders plot blocks (see React and Streamdown) shows as a chart too. Nothing leaves your machine. --image-links adds a plotdown.cc image link of the chart to that text, for hosts that show images of the model's answer but not those of a tool result; the link holds the block, so its data goes to whoever opens it.

Check it

Ask for a chart: "Plot the body mass of Adelie (3750 g) and Gentoo (5000 g) penguins as bars." The model calls render_plot, and the chart shows in the reply. To see the blocks it may write, read the spec or try one in the playground.

Notes

Remote data is off in the server and in the view: the data must be inline.
The skill teaches the format without a server, to models that only write Markdown: see agent skill.
As a library: createServer({imageLinks}) and startHttpServer({port, imageLinks}) are exported for a server of your own.

Note

Tried with @devlooped/plotdown-mcp 0.1.0 on Node 24 on 2026-11-12: an MCP SDK client called render_plot over stdio (with and without MCP Apps support) and over Streamable HTTP, and the packed package ran from npx outside the repository. The host configurations are from the hosts' documentation; the server was not tried in Claude, ChatGPT or VS Code yet.

Edit this page on GitHub