Support adding image descriptions

[lucaswerkmeister]

Twitter allows you to add descriptions (alt text) to images, to improve accessibility. It would be great if this client supported that as well.

[baedert]

They do not allow that from their public REST API as far as I can see, https://blog.twitter.com/2016/alt-text-support-for-twitter-cards-and-the-rest-api mentions a 1.1/media/metadata/create.json endpoint for which "documentation [...] will soon be published", but https://dev.twitter.com/rest/reference still doesn't list it.

[Vistaus]

@baedert I'm no dev, but it seems like twurl succesfully implemented it. Is that the way you can do it as well? (again: I'm no dev so I don't know whether this'll work or not) https://twittercommunity.com/t/alt-text-support-in-twurl/64391/5

[baedert]

Umm, I don't know if that works or not, https://dev.twitter.com/rest/reference/post/media/metadata/create looks like some unfinished placeholder site (and it even links to a chunked media upload endpoint that doesn't officially exist...?)

[lucaswerkmeister]

The twitter.com website seems to do mostly the same thing as twurl – this was POSTed to /i/media/metadata/create.json when I sent a tweet with a described image:

{"media_id":"830402076324794368","alt_text":{"text":"Two Agents Smith"}}

Same JSON as in comment #​5 there (modulo whitespace).

Also, the body of the subsequent POST request to /i/tweet/create contained &has_alt_text=true (along with the media ID).

[lucaswerkmeister]

It looks like the required API is now properly documented on https://developer.twitter.com/en/docs/media/upload-media/api-reference/post-media-metadata-create:

Call this endpoint to attach additional metadata such as image alt text.

POST https://upload.twitter.com/1.1/media/metadata/create.json

{
  "media_id":"692797692624265216",
  // image alt text metadata
  "alt_text": {
    "text":"dancing cat" // Must be <= 420 chars
  }
}