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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description contributes the cost signal ('Free', repeated) and the 'latest check' snapshot framing, but says nothing about what happens when no check exists or whether results are cached/fresh.

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?

One dense sentence front-loads the report contents efficiently, but the trailing 'Free. Free.' is a literal duplicate that wastes space and reads as an authoring error.

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, the description usefully enumerates the returned sections, which is the main completeness win. It still omits the failure/precondition path (no check run yet, unknown domain) and any indication of freshness, which an agent needs before calling.

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?

Single required website parameter with 100% schema description coverage, so the schema already carries the format example. The description adds no meaning about the parameter (e.g. whether a domain root or full URL is required, or how normalization works).

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 enumerates exactly what the report contains (overall visibility, trend, per-assistant breakdown, competitor rank, cited sites, next actions), so the resource is clear. It never names the sibling tools (visibility_check, visibility_answers) or explains how this differs from them, keeping it below a 5.

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?

There is no statement of when to reach for this tool versus visibility_check or visibility_answers, and no prerequisites such as whether a check must already exist. The only guidance-adjacent signal is 'Free', which speaks to cost rather than selection.

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