npm-registry-mcp-server

A Model Context Protocol (MCP) server that looks up package metadata from the npm registry, powered by package-json by Sindre Sorhus.

• Transport: stdio
• Validation: zod input/output schemas on every tool
• Monitoring: Sentry (@sentry/node) initialized before the server starts, with automatic MCP instrumentation via wrapMcpServerWithSentry
• Runtime: Node.js >= 18 (matches the package-json engines requirement)

Repository: https://github.com/yuchen814/npm-registry-mcp-server

Tools

get_package_metadata

Fetch metadata for a package from the npm registry.

Argument	Type	Required	Description
packageName	string	yes	Package name, scoped packages supported (react, @sindresorhus/df). Validated against npm naming rules.
version	string	no	Exact version (1.0.0), dist-tag (latest, next), or semver range (1, 1.2, ^1.2.3, ~1.2.3). Defaults to latest.
fullMetadata	boolean	no	Return full (non-abbreviated) metadata. Defaults to false.
allVersions	boolean	no	Return the registry main entry containing all versions. Defaults to false.
omitDeprecated	boolean	no	Omit deprecated versions when resolving ranges (explicit versions/dist-tags still resolve). Defaults to true.

Package-not-found and version-not-found conditions are reported as tool errors with clear messages (PackageNotFoundError / VersionNotFoundError from package-json).

get_package_versions

List every published version and all dist-tags of a package.

Argument	Type	Required	Description
packageName	string	yes	Package name, scoped names supported

Returns { name, distTags, versions, total } as structured content.

Install & run

npm install
npm run build
npm start          # runs node dist/server.js on stdio

Development (no build step):

npm run dev        # tsx server.ts

Try it with the MCP Inspector:

npm run inspector

Client configuration

Example entry for an MCP client such as Claude Desktop (claude_desktop_config.json):

{
	"mcpServers": {
		"npm-registry": {
			"command": "node",
			"args": ["/absolute/path/to/npm-registry-mcp-server/dist/server.js"],
			"env": {
				"SENTRY_DSN": "https://examplePublicKey@o0.ingest.sentry.io/0"
			}
		}
	}
}

Environment variables

Variable	Default	Description
SENTRY_DSN	(unset)	Sentry DSN. When unset, Sentry is disabled and the server runs normally.
SENTRY_ENVIRONMENT	production	Sentry environment tag.
SENTRY_TRACES_SAMPLE_RATE	0.1	Sample rate (0.0–1.0) for performance tracing of MCP requests.

Copy .env.example to get started. Registry selection (including private registries and auth) follows your .npmrc, exactly like npm itself, courtesy of package-json.

Error monitoring

Sentry.init() runs before the MCP server is constructed or connected. Expected lookup failures (unknown package/version) are returned to the client as tool errors and are not sent to Sentry; unexpected failures are captured and flushed before the tool responds. Fatal startup errors are also captured.

License

MIT