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

Annotations already mark this as a read-only, non-destructive, open-world operation. The description adds meaningful context beyond that: it only ever captures a fixed set of example pages and requires a separate account/API key to capture arbitrary URLs. It does not add rate-limit or auth-specific detail, but the key behavioral constraint is disclosed.

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 tight sentences with the purpose front-loaded and the limitation following immediately; nothing is wasted. The phrasing 'localscreenshot result' is slightly awkward, keeping it just short of ideal.

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?

With an output schema present and full param coverage, the description doesn't need to explain returns or parameters. It covers the essential scope constraint and the redirect to the real service. Sufficient, though a line naming the three available example pages would have eliminated any residual guesswork.

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% and both parameters are enums with documented options, so the schema fully carries parameter meaning. The description adds no parameter detail (it doesn't even mention that only three example pages exist), which is acceptable at this coverage level but earns only the baseline.

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 conveys that this returns a sample/preview screenshot of a fixed example page ('a real screenshot of one of our example pages'), which is a specific verb+resource. It also immediately clarifies the scope limitation. It does not differentiate against its siblings (get_pricing, list_countries), but those appear unrelated to screenshotting.

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?

It explicitly states the negative case — 'It does not capture a page of your choice' — and names the alternative path: create an account and use the main MCP server with an API key. An agent knows exactly when this tool is and isn't appropriate.

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