godoc and gotour can be built and run from their respecitve source directory with go build. What is the reason a gotour binary created when one go get it and that is not the case for godoc.

Command Line Output:

[ user@pc:~/.gvm/pkgsets/go1.5.1/global ]
>> ls

[ user@pc:~/.gvm/pkgsets/go1.5.1/global ]
>> go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/user/.gvm/pkgsets/go1.5.1/global"
GORACE=""
GOROOT="/home/user/.gvm/gos/go1.5.1"
GOTOOLDIR="/home/user/.gvm/gos/go1.5.1/pkg/tool/linux_amd64"
GO15VENDOREXPERIMENT=""
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"

[ user@pc:~/.gvm/pkgsets/go1.5.1/global ]
>> go get golang.org/x/tools/cmd/godoc

[ user@pc:~/.gvm/pkgsets/go1.5.1/global ]
>> ls
pkg  src

[ user@pc:~/.gvm/pkgsets/go1.5.1/global ]
>> go get golang.org/x/tour/gotour

[ user@pc:~/.gvm/pkgsets/go1.5.1/global ]
>> ls 
bin  pkg  src

[ user@pc:~/.gvm/pkgsets/go1.5.1/global ]
>> ls bin/
gotour

[ user@pc:~/.gvm/pkgsets/go1.5.1/global ]
>> cd src/golang.org/x/tools/cmd/godoc/

[ user@pc:~/.gvm/pkgsets/go1.5.1/global/src/golang.org/x/tools/cmd/godoc ]
>> go build

[ user@pc:~/.gvm/pkgsets/go1.5.1/global/src/golang.org/x/tools/cmd/godoc ]
>> ./godoc 
usage: godoc package [name ...]
    godoc -http=:6060
  -analysis string
        comma-separated list of analyses to perform (supported: type, pointer). See http://golang.org/lib/godoc/analysis/help.html
  -ex
        show examples in command line mode
  -goroot string
        Go root directory (default "/home/user/.gvm/gos/go1.5.1")
  -html
        print HTML in command-line mode
  -http string
        HTTP service address (e.g., ':6060')
  -httptest.serve string
        if non-empty, httptest.NewServer serves on this address and blocks
  -index
....

Godoc is special as it is an official tool being part of the Go distribution.

So if you go get godoc, the result binary will not be placed under $GOPATH/bin where all other executables go, but under $GOROOT/bin.

Gotour is not special in this way, so it gets installed into your $GOPATH/bin.

And for those just want to install godoc under $GOPATH can do so:

1. Download, don't install:

$ go get -u -d golang.org/x/tools/cmd/godoc

2. Build binary to specific path:

$ go build -o $GOPATH/bin/godoc golang.org/x/tools/cmd/godoc