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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It covers key behavioral aspects: returns a short-lived, single-device URL, requires a human to open it in a browser, live transcoding to MJPEG. It doesn't mention how long 'short-lived' actually is or any auth/access constraints on the URL, but covers the essential delivery mechanism and purpose.

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?

Four sentences, each adding distinct value: purpose, output details, mechanism, and use case. It's slightly verbose with the transcoding sentence being a nice-technical detail rather than essential action guidance, but overall efficient and well-structured.

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?

For a single-parameter tool with no output schema and no annotations, the description covers the main things an agent needs: what it returns (a live URL), who consumes it (a human), how it differs (real-time vs screenshot), and when to use it (supervise agent actions on device). It could mention the URL's exact lifetime, but the description is quite complete for this simple tool.

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?

Schema description coverage is 100%, so the schema already documents the udid parameter. The description doesn't add parameter-specific detail beyond what the schema provides, but there's only one parameter and its purpose (device identifier) is self-evident. Baseline 3 is appropriate and slightly above due to the clarity of the single parameter context.

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 uses a specific verb+resource: 'Get a LIVE video-stream link for an Android device that a human can open in a browser to watch the screen in real time.' It clearly distinguishes from device_screenshot (one frame) and android_mjpeg_screenshot siblings, and communicates the live, human-viewable nature of the output.

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 states when to use this tool ('Use this to let a person supervise what the agent is doing on the device') and contrasts with device_screenshot for single-frame needs. It lacks explicit exclusion guidance for other streaming alternatives like android_mjpeg_screenshot or device_record_start, but the context of use is clearer than most sibling tools.

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