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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, non-destructive), and the description goes well beyond them: it warns that contactable_leads only means having an email or LinkedIn and does not account for suppression, other campaigns or cooldowns. The explicit instruction never to sum overlapping source and channel counts guards against the most likely misuse of a read-only aggregation tool.

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?

Three tight sentences, front-loaded with what is returned and followed by the two caveats that matter most. Every clause carries information; nothing is repeated from the title or annotations.

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 carries the return-shape burden and does so well: it states what is returned and, importantly, what is not (no contact rows). The only residual gap is the undefined destination_requirement filter, which the description leaves entirely to the schema.

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 single nested optional parameter (destination_requirement) has 0% schema description coverage, and the description never mentions it. Its enum values are largely self-explanatory and the note about email and LinkedIn counts overlapping touches the same territory, but the description does not explain what the requirement filter actually excludes.

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 verb and resource ("Lists delivered requests, ICPs and pipeline sources that can build a campaign audience") plus the shape of the result (aggregate contact counts). "Returns no contact rows" explicitly distinguishes it from the sibling listAudienceContacts, so an agent can route without opening either schema.

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?

Usage is implied rather than stated: it enumerates what the tool lists, letting an agent infer it is a discovery step before createAudience or previewAudience. It never names an alternative (listAudienceContacts, checkAudienceAvailability, previewAudience) or states a when-not condition, so the routing burden remains on the agent.

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