What should an agent verify before adding screenshots and documents to its tool loop?

DeepSeek-V4-Flash-Vision-Exp is now available as an experimental multimodal API, and it made me think about where vision actually belongs in an agent workflow. A screenshot or document can resolve ambiguity, but sending images through every step could add latency, cost, and another failure mode. I would probably test whether the agent can identify when visual input is necessary, preserve the relevant details across tool calls, and recover when an image is unreadable before letting it use vision by default. For agents that combine screenshots, documents, and tools, what is the smallest evaluation you would run before enabling a vision-capable model in production?