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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds value beyond them by labeling the data as 'Live' (freshly computed rather than a cached snapshot) and by sketching the dimensions of the breakdown returned — important since there is no output schema.

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?

A single front-loaded sentence with the payload metric named first and the dimensions listed after. The marketing flourish 'the honest answer to...' earns its place by conveying the intended use, but it is the softest part of the sentence.

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 zero-param aggregate tool with no output schema, the description must convey the response shape, and it only lists noun categories without field names, nesting, or whether counts are global or per-adapter. It is adequate to decide to call it, but not to interpret the result 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?

The tool takes zero parameters, so per the rubric the baseline is 4 only when the description is not misleading. Here the term 'distinct surfaces' and 'verified ops' are undefined aggregate concepts whose meaning an agent must guess, and no scope (global vs per-adapter) is stated, which weakens interpretation rather than the parameter layer itself.

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?

Names a specific resource (coverage metrics) and enumerates what it aggregates: adapters, distinct surfaces, verified ops, and a status/kind breakdown. That is enough to separate it from listing-style siblings such as wide_adapters, though no sibling is named explicitly.

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?

The framing question 'how many surfaces can agents act on?' implies the use case (getting aggregate counts rather than enumerating rows), which is real guidance. It stops short of explicit when-to-use/when-not rules or naming wide_adapters or wide_offer_stats as the alternative for detail-level queries.

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