How can I run a script from an already installed NPM package?

Example:

npm install my-tools
npm run my-tools tool1

This doesn't work - it looks for a "package.json in my current directory. The documentation for "npm run" says:

If no package name is provided, it will search for a package.json in the current folder

(http://ift.tt/1BdXhm8)

So how can I provide a package name?