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@cpp.js/mcp

Model Context Protocol server for cpp.js. Gives any MCP-compatible coding agent (Claude Desktop, Claude Code, Cursor, Codex, Cline, …) typed access to the cpp.js toolchain — recommend the right workflow, detect a project's bundler, list prebuilt packages, scaffold new ones, and run builds.

Not Claude-specific. MCP is a vendor-neutral standard; this server speaks JSON-RPC over stdio and works with every client that supports MCP.

Install​

The server is published to npm and runs via npx. No global install needed.

Claude Desktop​

Edit ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
    "mcpServers": {
        "cppjs": {
            "command": "npx",
            "args": ["-y", "@cpp.js/mcp"]
        }
    }
}

Claude Code​

claude mcp add cppjs -- npx -y @cpp.js/mcp

Cursor​

Settings → MCP → Add new MCP server. Paste:

{
    "mcpServers": {
        "cppjs": {
            "command": "npx",
            "args": ["-y", "@cpp.js/mcp"]
        }
    }
}

OpenAI Codex CLI​

Add to ~/.codex/config.toml (or per-project .codex/config.toml):

[mcp_servers.cppjs]
command = "npx"
args = ["-y", "@cpp.js/mcp"]

Or via Codex CLI:

codex mcp add cppjs --command "npx -y @cpp.js/mcp"

GitHub Copilot CLI​

Copilot CLI auto-discovers MCP servers from the active plugin's .mcp.json. The cpp.js Copilot plugin (cppjs-agents/.github/plugin.json) references cppjs-agents/.mcp.json, which registers cppjs automatically when the plugin is installed.

Manual install (without the plugin):

copilot mcp add cppjs npx -y @cpp.js/mcp

Google Gemini CLI​

Either install the cpp.js Gemini extension (which wires this MCP server automatically):

gemini extension install https://github.com/bugra9/cpp.js

Or add manually to your ~/.gemini/settings.json:

{
    "mcpServers": {
        "cppjs": {
            "command": "npx",
            "args": ["-y", "@cpp.js/mcp"]
        }
    }
}

OpenCode​

Add to opencode.json (global at ~/.config/opencode/opencode.json or project-level):

{
    "mcp": {
        "cppjs": {
            "type": "local",
            "command": ["npx", "-y", "@cpp.js/mcp"],
            "enabled": true
        }
    }
}

Cline / other MCP clients​

Use the same JSON shape. The command is always npx -y @cpp.js/mcp; transport is stdio.

Working directory​

For the build / scaffold / check / doctor tools, the server must be launched from inside a cpp.js monorepo checkout (it walks up looking for pnpm-workspace.yaml + cppjs-core/ + cppjs-packages/). The detect_framework / list_packages / recommend tools work anywhere — they don't need the monorepo.

To pin the working directory, override cwd in your MCP client config (most clients support it), or wrap the command:

{
    "mcpServers": {
        "cppjs": {
            "command": "npx",
            "args": ["-y", "@cpp.js/mcp"],
            "cwd": "/path/to/your/cpp.js/checkout"
        }
    }
}

Tools​

ToolNeeds monorepo?What it does
cppjs_recommendnoGiven a use-case description, route to integrate / package / inline workflow + the right playbook.
cppjs_list_packagesnoCatalog of 16 prebuilt @cpp.js/package-* libraries (gdal, openssl, geos, sqlite3, …). Filter by category.
cppjs_detect_frameworknoDetect bundler / runtime of a project (vite, webpack, rspack, rollup, nextjs, RN-cli, RN-expo, cloudflare-worker, nodejs, vanilla).
cppjs_scaffold_packageyesCreate a new cppjs-package-<name> family from the zlib template.
cppjs_doctoryesVerify Node / pnpm / Docker / Android SDK+NDK / Xcode prerequisites.
cppjs_build_packageyesRun pnpm --filter '@cpp.js/package-<name>*' run build for the requested arches.
cppjs_check_native_versionsyesCompare each package's nativeVersion against the latest upstream release; optionally auto-bump.
cppjs_cloud_build_packagenoPlaceholder for a future hosted build service. Returns "not implemented" + local-build alternatives.

Pairs with the Claude Code plugin​

The cppjs Claude Code plugin (in this same repo under cppjs-agents/) ships the same workflows as slash commands (/cppjs-integrate, /cppjs-package, /cppjs-bug-fix) and skills that auto-trigger on user phrases. Skills tell the agent how to think; this MCP gives it function calls. Use both together for the best experience.

Reference​