@moonarc/mcp

MCP server for Moonarc. Local, stdio, no account.

claude mcp add moonarc -- npx -y @moonarc/mcp

Cursor, VS Code and Codex take the same command in their own config files: moonarc.dev/mcp has each one.

Tools: search_motion(intent, max_js_bytes?, tier?, limit?), get_component(name), get_install_command(names, method?), get_usage(). The catalogue is bundled at publish time. MOONARC_CATALOG_URL reads a catalogue of the same shape from a URL instead, a mirror or a test's; when that URL fails, takes over 5 s or answers another shape, the bundled copy answers.

Pro

With a Pro key in MOONARC_KEY, three more tools appear: audit_motion(paths, format?), measure_budget(dist, ceiling?, base?, format?) and compose_section(intent). The server asks Polar whether the key is valid and keeps a definite answer for the life of the process. Without a key and without MOONARC_CATALOG_URL, it makes no network request.

The client starts the server, and most clients pass it only a few of your environment variables, so put the key in the client's config:

• Claude Code: claude mcp add --env MOONARC_KEY=<your key> --transport stdio moonarc -- npx -y @moonarc/mcp (keep an option between --env and the name, or the CLI reads the name as another variable)
• Cursor, in .cursor/mcp.json: "env": { "MOONARC_KEY": "${env:MOONARC_KEY}" } beside command
• VS Code, in .vscode/mcp.json: an input { "type": "promptString", "id": "moonarc-key", "password": true } and "env": { "MOONARC_KEY": "${input:moonarc-key}" }
• Codex, in ~/.codex/config.toml: env_vars = ["MOONARC_KEY"] under [mcp_servers.moonarc]

get_usage tells you which plan the server validated.

The same package runs the audit and the byte meter as commands, for CI:

npx -y @moonarc/mcp audit src
npx -y @moonarc/mcp measure dist --ceiling 30000

audit exits 1 when it finds an error. measure reads the folder astro build wrote (a server build's dist/client is found by itself), takes --ceiling in raw bytes per page and --base when the site sets one, and exits 1 when a page is over the ceiling. Both exit 2 on a usage mistake, a refused key or a folder that is not a build.