Agent Image capability doesn't advertise acceptable image types

[dmeehan1968]

I tried sending an image content block of type image/svg+xml to Claude, and received API Error: 400 Could not process image.

I checked the code for claude-agent-acp used as the adapter, and it appears to pass them through transparently, so the failure came from Claude itself.

In the initialise response, the agent advertises a boolean image agent capability, but if its then going to reject images without a specific error annotating which image is unacceptable, the client has to either drop all images or fail the prompt entirely until the user corrects. In my case I'm forwarding images embedded in GitHub issues which I have little control over, and specifically this was a bot inserted comment (my client takes image references and attaches them as image blocks to get around private repo attachments).

One could argue that the agent shouldn't be rejecting prompts on the basis of invalid mime type or image content, but merely feeding back to the user that it can't process the image, rather than rejecting the prompt wholesale. However it seems sensible that the agent capabilities should provide either a whitelist or blacklist of acceptable image type if this behaviour is prevalent.