Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the transparency burden and does well: it discloses the short-lived nature, single-device constraint, direct openability in a browser, and on-the-fly MJPEG transcoding. It could additionally clarify URL expiration duration or any stream lifecycle/cleanup expectations, but the core behavior is clear.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured and front-loads the primary purpose. The four sentences each provide distinct value, though the 'live/real time/on the fly' phrasing is slightly redundant.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description explains the return type (a short-lived viewer URL), the mechanism (MJPEG transcoding), and the intended use. With no output schema, it provides enough for an agent to select and invoke the tool, though exact URL expiration or auth requirements are not specified.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There is only one parameter (udid), and the input schema already describes it as 'Device serial number (UDID)' with 100% coverage. The description does not add meaning beyond the schema, but none is really needed for such a simple parameter.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool fetches a live video-stream link for an Android device, for real-time human viewing in a browser. It explicitly contrasts with device_screenshot (single frame), which disambiguates from the most similar sibling.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives a clear use case: 'let a person supervise what the agent is doing on the device.' It also names device_screenshot as a non-live alternative. However, it does not explicitly mention when to prefer or avoid other related tools such as android_mjpeg_screenshot or ios_video_stream.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.