Version for package `Microsoft.EntityFrameworkCore.Tools.DotNet` could not be resolved

There isn't a 1.0.1 version of Microsoft.EntityFrameworkCore.Tools.DotNet (at the time of writing). You need to set Version="1.0.0" in order to restore the package.

The available versions are listed on NuGet.

Update:

To use CLI tools, you first need to add <DotNetCliToolReference> items as you have already have.

Then you call dotnet restore in the directory of the project to download the packages to your local cache, then the tool becomes usable and dotnet ef can be used.

What helped in my case(.NET Core 2.0.3) was to issue:

dotnet add package Microsoft.EntityFrameworkCore.Design

And then

dotnet restore

This installed the Microsoft.EntityFrameworkCore.Tools.DotNet in a correct version