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

Annotations already establish readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds genuine value beyond that by flagging a trap in the payload — that messageReadyNow and messageBlocked are placeholder echoes without campaign message settings and must not be cited. It stops short of saying what happens with an invalid or expired snapshotId.

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, zero filler, with the tool's purpose front-loaded and the output caveat second. The warning about misleading fields is placed after the purpose so it is read at the moment it matters.

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 carries the burden of return semantics and it does that well for the two trap fields. However, for a nested two-parameter tool with 0% schema coverage, it leaves both input parameters undefined, which is a real gap for correct invocation.

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 0% and the description never mentions either input. snapshotId (a UUID identifying the saved audience) is only nameable by inference, and the query.destination_requirement enum with its four email/linkedin combinations is entirely unaddressed despite materially changing the counts returned.

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 gives a specific verb and resource ('Returns a saved audience's status, freshness and eligibility counts') plus the intended outcome ('confirm it is ready before creating a campaign'). It does not explicitly distinguish itself from nearby siblings such as checkAudienceAvailability, previewAudience or getAudienceFunnel, which sound close enough that an agent could hesitate.

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?

It clearly states the moment to use it: as a preflight check before creating a campaign. It gives no explicit when-not conditions or named alternatives (e.g. use listAudiences to discover snapshotIds, previewAudience to inspect members), so the boundary with siblings is left to inference.

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