@oh-just-another/mcp

MCP (Model Context Protocol) server for LLM agents. Exposes headless scene tools — create, edit, query, render — over stdio. No browser, no network IO.

Install

npx @oh-just-another/mcp        # run directly
pnpm add @oh-just-another/mcp   # or install; binary: oja-mcp
pnpm add @resvg/resvg-js        # only needed for export_png

Client config (Claude Desktop / Claude Code / any MCP client):

{
  "mcpServers": {
    "oja": { "command": "npx", "args": ["-y", "@oh-just-another/mcp"] }
  }
}

Tools

| Tool | Purpose | | ----------------------------------------------- | ----------------------------------------------------------------------------------- | | create_scene | New empty scene → sceneId. Scenes live in process memory for the session. | | load_scene(json) / get_scene(sceneId) | Serialized scene document in / out (validated, migrated). | | add_elements(sceneId, elements) | Add elements; validated against the scene schema, missing base fields get defaults. | | update_element(sceneId, id, patch) | Shallow-merge a patch (style deep-merged), revalidate. | | remove_elements(sceneId, ids) | Delete elements by id. | | add_link(sceneId, from, to, routing?, label?) | Connect two elements with an arrow (straight / orthogonal / bezier). | | query_scene(sceneId) | Compact summary: counts, content bounds, elements with id/type/text. | | export_svg(sceneId) | SVG string. | | export_png(sceneId, scale?) | Base64 PNG. Requires optional peer @resvg/resvg-js; clear error when missing. | | import_mermaid(text) | Mermaid flowchart → new scene → sceneId. | | get_scene_schema | JSON Schema of the serialized scene document. |

Programmatic use

import { createMcpServer, SceneStore } from "@oh-just-another/mcp";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";

await createMcpServer(new SceneStore()).connect(new StdioServerTransport());

Tool handlers (createScene, addElements, queryScene, …) are exported and callable directly against a SceneStore — no transport needed, useful for tests and embedding.