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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds the useful detail that the return is the captured image itself, but says nothing about failure modes (invalid uid) or image format/size.

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?

Three short sentences, front-loaded with the action and return, then the parameter derivation. No filler or repetition of the title.

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, no-output-schema read tool, the description covers what it does, what comes back, and how to obtain the id. Only minor gaps remain (error behavior, image format), which are not essential to invoking it correctly.

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 coverage is 0% and the schema only says 'string', so the description carries the burden and does so well by defining uid as the last path segment of an images[].url from list_site_screenshots. It stops short of giving a literal example, but the derivation rule is actionable.

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?

States a specific verb and resource (get a screenshot image) and clarifies the return is the image FeelingSurfViewer captured. It also implicitly distinguishes itself from list_site_screenshots by referencing it as the source of uids, though it never says so explicitly as a contrast.

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 tells the agent exactly where the uid comes from (the last path segment of an images[].url from list_site_screenshots), which effectively routes usage from the list tool to this one. No explicit when-not-to-use guidance is given, but the workflow context is clear.

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