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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world), and the description adds real context beyond them: the payload is image content, availability is limited to reachable domain matches, and the response bundles a dashboard link because many clients do not surface tool images. It does not spell out the exact failure shape when no screenshot exists, which keeps it from a 5.

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 sentences, front-loaded with what is returned, then availability, then the dashboard-link fallback. Every sentence carries information; the client-rendering caveat is slightly verbose but genuinely actionable.

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, so the description must describe the return value — and it does: image content plus the match's dashboard link for the full-page capture. Availability constraints and the client-rendering caveat round out everything an agent needs to call and interpret this 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 100% and the single parameter is already documented as 'Match id from list_matches.' The description reinforces that the id must refer to a domain match but adds no format, sourcing, or edge-case detail beyond the schema — the baseline 3 for schema-documented parameters.

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 the screenshot captured for a domain match') and pins down exactly which capture: 'the top of the rendered page, the same view the assessment reads.' The 'as image content' framing cleanly separates it from metadata siblings like get_match and from get_match_evidence, so an agent can choose without opening the 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?

Gives a concrete precondition — 'Only domain matches with a reachable site have one' — which tells the agent when this call can legitimately fail or return nothing. It also guides consumers toward the embedded dashboard link when images are not rendered. It stops short of naming an explicit alternative tool for the no-screenshot case.

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