How can I tell if a given git tag is annotated or lightweight?

I type git tag and it lists my current tags:

1.2.3
1.2.4

How can I determine which of these is annotated, and which is lightweight?

Solution

git for-each-ref tells you what each ref is to by default, its id and its type. To restrict it to just tags, do git for-each-ref refs/tags.

[T]he output has three fields: The hash of an object, the type of the object, and the name in refs/tags that refers to the object. A so-called "lightweight" tag is a name in refs/tags that refers to a commit¹ object. An "annotated" tag is a name in refs/tags that refers to a tag object.

- Solomon Slow (in the comments)

Here is an example:

$ git for-each-ref refs/tags                                           
902fa933e4a9d018574cbb7b5783a130338b47b8 commit refs/tags/v1.0-light
1f486472ccac3250c19235d843d196a3a7fbd78b tag    refs/tags/v1.1-annot
fd3cf147ac6b0bb9da13ae2fb2b73122b919a036 commit refs/tags/v1.2-light

with some format:

$ git for-each-ref \
  --format="%(if:equals=tag)%(objecttype)%(then)a %(else)%(if:equals=blob)%(objecttype)%(then)b %(else)  %(end)%(end)%(align:20,right)%(refname:short)%09%(objectname:short)%(end)%09%(if:equals=tag)%(objecttype)%(then)@%(object) %(contents:subject)%(else)%(end)" \
  --sort=taggerdate \
  refs/tags

    v1.2-light  fd3cf14 
b       forsam  633de05 
a   v1.1-annot  1f48647 @1e25186bcf26d260754b6ebf6b236e92eeadc69b annotation comment
    v1.0-light  902fa93

To do this for just one ref, you can use git cat-file -t on the local ref, to continue the example:

$ git cat-file -t v1.0-light
commit
$ git cat-file -t v1.1-annot
tag

^{¹ tags can refer to any Git object, if you want a buddy to fetch just one file and your repo's got a git server, you can git tag forsam :that.file and Sam can fetch it and show it. Most of the convenience commands don't know what to do with tagged blobs or trees, but the core commands like update-index and such do}