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

Beyond the readOnly/idempotent/non-destructive annotations, the description discloses output behavior ('not-collected with null metrics'), data availability ('only the retained current observation is available; historical batch queries are not accepted'), and verification state (documentation not reviewed, vendor integrations untested). That is meaningful behavioral context, even if awkwardly worded.

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?

It is a run-on sequence of negative clauses rather than a front-loaded purpose statement. The most important information (what the tool returns) is buried after an opening clause that denies its own function.

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 7 parameters, 29% schema coverage, no output schema, and complex conditional allOf constraints, the description should do more. It gestures at output behavior but leaves most parameter semantics and the relationship to sibling tools unexplained.

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 description coverage is only 29% across 7 parameters, so the description must compensate but does not. Terms like 'matched/guide entries' and 'interfaces' only loosely gesture at sortBy values (search_appearance, integration_redirect) and never explain days, metric, scene, capability, or locale.

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 name implies listing rankings, but the description says the candidate set 'has no ranking evidence' and to 'Return not-collected with null metrics', which partially undercuts the stated resource. It never crisply states the verb+resource the tool performs, and it does not distinguish itself from the sibling list_rankings.

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 an implicit lane distinction ('Registry candidates do not enter the formal catalog rankings') and a constraint ('historical batch queries are not accepted'), but no explicit when-to-use guidance or named alternative between candidate_list_rankings and list_rankings. The agent must infer the routing.

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