@chanmeng666/archlang-mcp

A Model Context Protocol server for ArchLang — author, inspect, and repair architectural floor plans written as code, from any MCP-speaking host.

It is a thin stdio shim over the @chanmeng666/archlang library (no subprocess, no re-implementation): each tool wraps one pure, exported function. The core stays zero-dependency — the MCP SDK lives only in this package.

When to prefer the CLI

ArchLang's primary agent interface is the agent-native arch CLI, not this server. A CLI costs nothing in an agent's context window until it is called, whereas an MCP tool schema sits in the window permanently. If your agent already has a shell, prefer:

npx @chanmeng666/archlang context     # the whole language + workflow + CLI + errors, one call
npx @chanmeng666/archlang compile plan.arch -o out.svg --json

This MCP server exists so MCP-native hosts can discover ArchLang through the registry and drive it without a shell. It is listed on the official MCP registry as io.github.ChanMeng666/archlang-mcp. It is the discoverability channel, not a replacement. See ADR 0012 (which amends ADR 0009's distribution-over-protocol stance).

Tools

Every tool takes ArchLang source (a plan "…" { … } string) and returns structured JSON. compile also accepts plan_json (the Plan-JSON / RPLAN shape).

| Tool | What it does | |------|--------------| | compile | Render source (or plan_json) to SVG, or to zero-dep ASCII (format:"txt"). accessible, overlay:"circulation" opt-ins. Returns output + diagnostics. A multi-storey plan returns every storey in pages[]; level renders one. | | describe | Semantic facts (rooms, areas, adjacency, doors, circulation, zones, storeys, the exact floor_polygon/floor_circle shape, and a freedom report of which positions are hand-authored vs resolver-derived) — verify intent without an image. | | lint | Advisory W_* soundness warnings (may include the fix-carrying W_ALIAS_MATCH for a room use inferred from an indirect label alias); profile selects a ruleset. | | validate | Parse + resolve + lint, the ship gate. strict fails on warnings; graph checks interior-door adjacency against an intended room graph; intent gates on a brief's contract (per archlang://intent-schema). | | score | The continuous intent METER: how much of a brief a plan satisfies (satisfied/total/score/subscores). Measures, never gates. | | repair | Explicit corrector: furniture out of walls/doorways/swings → new .arch source + change log. Never adds doors/windows. | | fix | Apply the machine-applicable fixes on a plan's diagnostics (syntactic corrector; bounded fixpoint). unsafe widens to maybe-incorrect. | | suggest | Advisory door/window statements (each referencing its wall by a stable ref — an authored id or a unique category — or absolute coordinates, never a re-bindable positional id) to resolve unreachable rooms / windowless bedrooms — data, never applied. | | complete | LSP completion items in scope at a source byte offset. |

Resources

| URI | Content | |-----|---------| | archlang://spec | The whole language in one page (spec.llm.md). | | archlang://context | Full agent context: spec + workflow + CLI reference + error catalog (llms-full.txt). | | archlang://schema | JSON Schema (2020-12) for the Plan-JSON compile input. | | archlang://grammar | GBNF constrained-decoding grammar for guaranteed-parseable generation. | | archlang://intent-schema | JSON Schema (2020-12) for a brief's Intent — the shape validate's intent and score's brief take. |

Install

Claude Code

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

Claude Desktop

Add to claude_desktop_config.json (Settings → Developer → Edit Config):

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

Cursor

Add to .cursor/mcp.json (project) or ~/.cursor/mcp.json (global):

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

VS Code

Add to .vscode/mcp.json:

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

License

MIT © Chan Meng