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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is fully covered. The description adds that results are 'paged' (implying cursor-based navigation) and discloses return contents (answers, mentions, cited sources), but says nothing about auth needs, rate limits, or what empty results mean.

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, front-loaded with what the tool returns before the usage clause. No filler; every clause carries information about either output or filtering.

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 no output schema and only 22% param coverage across 9 params, the description should carry more weight. It sketches the return shape (answers, mentions, sources) and the main filters, but omits pagination mechanics, engine/cohort selection, and result semantics for an agent to invoke confidently.

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 only 22% and there are 9 params, so the description must compensate more than it does. It usefully explains the intent behind the filter params (prompt_id, domain, url) as a means 'to read fewer', but leaves engine, cohort, limit and cursor undescribed beyond what the schema's enums/defaults already imply.

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 names a specific resource - 'the answers engines gave in one run, with mentions and cited sources' - which an agent can distinguish from sibling read tools like read_visibility_overview (audit-level) or read_visibility_trends (time series). It is clear and concrete, though it doesn't explicitly contrast itself with read_visibility_sources, which also concerns sources.

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?

'Use it to see what an engine said for a prompt' gives a clear use context, and 'filter by prompt_id, cited domain or URL to read fewer' tells the agent how to narrow results. It lacks explicit when-not-to-use guidance or named alternatives among the many read_visibility_* siblings.

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