Yeah, the raw JSON (in my case) is the result of a failed tool call, it was trying to generate an image. With thinking models, you can observe the degeneration

Yeah, the raw JSON (in my case) is the result of a failed tool call, it was trying to generate an image. With thinking models, you can observe the degeneration of its understanding of image tool calls over the lifetime of a chat. It eventually puzzles over where images are supposed to be emitted, how it's supposed to write text, if it's allowed to provide commentary - and eventually, it gets all of it wrong. This also happens with file cites (in projects) and web search calls.