Observe

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

No annotations are provided, so the description carries the full disclosure burden, and it does useful work: "Sections are independent — one failing does not lose the rest" tells the agent that partial results are a normal outcome rather than a hard error. It does not mention that the tool is read-only, the cost or latency of capturing a full snapshot, or what the default device is when the device parameter is omitted.

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?

Two sentences, no filler, with the payload description front-loaded and the routing preference and failure-tolerant behavior in the second. Every clause adds information an agent needs.

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?

There is no output schema and no annotations, so the description must explain what the agent gets back, and it only names the four sections without describing their shape or size. Combined with the unexplained parameters, an agent knows when to call this but not how to configure it or what the payload will look like.

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 0%, so all four parameters (device, source, full_res, screenshot) are undocumented in both the schema and the description. The words "screenshot" and "full" appear in prose, but the description never explains what these flags do, what the js/os/auto source enum means, or what the defaults are.

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?

"One-shot snapshot of the screen" states a specific verb+resource, then enumerates exactly what is bundled (screenshot, interactive elements, recent errors, recent logs). This is enough to distinguish it from the sibling tools screenshot, get_layout, and get_logs without opening any schema.

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?

"Prefer this over separate screenshot/get_layout/get_logs calls" gives an explicit routing rule with the alternatives named, which is exactly the guidance an agent needs. It stops short of saying when this tool should NOT be used, for example when only logs are needed or full-resolution fidelity is required.

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