ArchLang

Floor plan MCP server ​

ArchLang is an open-source language for floor plans, created by Chan Meng: you write .arch text and compile it to SVG, DXF or PDF.

Its MCP server lets an AI agent in an MCP host (Claude Desktop, Claude Code, Cursor, VS Code, claude.ai and others) draw a floor plan: the model writes .arch text, and the server's tools compile it, describe it, lint it and fix it. There are two ways to connect, the same tools in both:

ServerHow it runs
@chanmeng666/archlang-mcpA local stdio server, run with npx. Listed on the official MCP registry as io.github.ChanMeng666/archlang-mcp.
https://mcp.archlang.uk/mcpA hosted Streamable HTTP server. No sign-in and no install; plan sources up to a size cap, rate-limited per address, no PNG output.

If the agent can run shell commands, the CLI does the same work and costs nothing in the context window until it is called; an MCP server's tool list sits in the context all the time. The MCP server is for hosts without a shell, and for people who prefer to install a server.

Install the floor plan MCP server ​

Claude Code:

bash
claude mcp add archlang -- npx -y @chanmeng666/archlang-mcp

Claude Desktop (claude_desktop_config.json) and Cursor (.cursor/mcp.json):

json
{
  "mcpServers": {
    "archlang": {
      "command": "npx",
      "args": ["-y", "@chanmeng666/archlang-mcp"]
    }
  }
}

VS Code (.vscode/mcp.json):

json
{
  "servers": {
    "archlang": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@chanmeng666/archlang-mcp"]
    }
  }
}

claude.ai, or any host that takes a remote server: add https://mcp.archlang.uk/mcp as a custom connector, with no authentication. In claude.ai, and other hosts that support MCP Apps, the compile result is shown in a viewer you can pan and zoom.

What the tools do ​

ToolWhat it does
compileSource to SVG (or ASCII, Plan JSON, or PNG on the local server), with diagnostics.
describeRooms, areas, adjacency, what each door connects, reachability from the entrance.
lintAdvisory warnings: a windowless bedroom, a bathroom reached through a bedroom, a narrow door.
validateThe ship gate: parse, resolve and lint, optionally strict or against a brief.
scoreHow much of a written brief a plan satisfies, as a number.
fixApplies the machine-applicable fixes the diagnostics carry.
repairMoves furniture out of walls, doorways and door swings.
finishFurnishes empty rooms and adds paper, scale, dimensions, title, schedule and legend.
suggestDoor and window statements that would fix an unreachable room or a windowless bedroom.
completeCompletion items at a position in the source.
linkA playground URL that opens the plan in a browser.

The hosted server adds read_me, which says what the server is and what it keeps. Both servers also expose the language as resources: archlang://spec (the whole language on one page), archlang://context, the Plan JSON and intent schemas, and the GBNF grammar.

An AI agent drawing a floor plan ​

Asked for "a garden studio with a shower room, entered from the south", an agent reads archlang://spec, then writes something like this and passes it to compile:

arch
plan "Garden studio" {
  units mm
  grid 50
  room id=studio at (0,0)        size 5000x3600 label "Studio" uses living
  room id=shower right-of studio size 1800x3600 label "Shower room" uses bath
  walls from rooms exterior 200 partition 100
  door on studio.bottom at center width 900 swing into studio
  door between studio and shower at 1800 from start width 800 swing into shower
  window on studio.top width 1800
  furniture shower in shower anchor top flush size 900x900
  furniture basin against shower.right
  furniture wc against shower.bottom
}

describe then confirms two rooms, 18 m² and 6.48 m², both reachable from the entrance, and lint returns no warnings. An earlier draft put the basin beside the shower-room door, and lint returned four warnings, among them W_SWING_OBSTRUCTED: the door needs 800 mm of clear swing and the basin stood 206 mm from the hinge. That loop — write, compile, read the facts and warnings, edit — is what the tools are for, and it needs no image.

FAQ ​

Is there an MCP server for floor plans? ​

Yes. @chanmeng666/archlang-mcp is an MCP server for ArchLang floor plans. Run it locally with npx -y @chanmeng666/archlang-mcp, or connect to the hosted one at https://mcp.archlang.uk/mcp.

Can an AI agent draw a floor plan? ​

Yes, by writing it as text. The agent writes ArchLang source, the compile tool draws it as SVG, and describe and lint tell the agent the room areas, what each door connects and what is wrong, so it can check the plan against the brief without looking at the drawing. The agent gallery shows plans agents wrote from one-paragraph briefs.

Does the hosted MCP server need an account or an API key? ​

No. https://mcp.archlang.uk/mcp has no sign-in. It keeps no plan source and no request logs; the privacy page says what it does keep.

Should I use the MCP server or the CLI? ​

Use the CLI when the agent has a shell: npx -y @chanmeng666/archlang context gives it the whole language in one call, and nothing sits in its context until it runs a command. Use the MCP server when the host has no shell, or when you want the tools listed in the host's UI.

Next ​